STATE BUDGET EDUCATIONAL INSTITUTION OF HIGHER PROFESSIONAL EDUCATION
PYATIGORSK STATE PHARMACEUTICAL ACADEMY OF THE FEDERAL AGENCY
ON HEALTH AND SOCIAL DEVELOPMENT" Department of Botany
M.A. Galkin, L.V. Balaban, F.K. Silver
Botany
Lecture course
Textbook for independent work of 1st-2nd year students (2nd and 3rd semesters)
in the discipline "Botany" (C2.B9) (full-time and part-time study)
Second edition, expanded, illustrated
Pyatigorsk 2011
UDC 581.4"8(076.5)
BBK 28.56ya73 L 16
Reviewer: Konovalov D.A., Doctor of Pharm. Sc., Professor, Department of Pharmacognosy, Pyat State Physics Academy
L16 Botany: Lecture course. A textbook for independent work of 1st-2nd year students (2nd and 3rd semesters) in the discipline “Botany” (C2.B9) (full-time and part-time study)/ M.A. Galkin, L.V. Balaban, F.K. Serebryannaya.- Pyatigorsk: Pyatigorsk GFA, 2011.- 300 p.
An illustrated lecture course on botany compiled in
in accordance with the Federal State Educational Standard for Higher Professional Education 3rd generation, the botany program for
pharmaceutical universities, includes five sections - morphology, anatomy,
taxonomy, geography, plant physiology. The course was based on lectures
read for 1st and 2nd year students by teachers of the Department of Botany
Pyat State Faculty of Physics (head of department Prof. Galkin M.A.). The lecture course is intended
to prepare for laboratory classes in botany, full-time and part-time
departments, for independent extracurricular work of students of Pyat State Faculty of Physics, and
also for distance learning of correspondence students.
UDC 581.4"8(076.5)
BBK 28.56ya73 L 16
Admitted to the intra-university publication by the Chairman of the Center for Medical Sciences, V.V. Gatsan Professor Protocol No. 15 of March 5, 2011
©GOU VPO Pyatigorsk State Pharmaceutical Academy, 2011
INTRODUCTION
In recent years, there has been an undoubted increase in interest in distance learning and self-education. The goal that the authors set for themselves is to increase the efficiency and quality of training, and
also intensification of the educational process. When compiling a course of lectures, the authors tried not only to cover the entire theoretical basis of botany, but also to qualitatively illustrate the work to sufficiently visualize the student’s knowledge.
The purpose of studying botany at a pharmaceutical university is determined by the Federal State Educational Standard for Higher Professional Education in the specialty 060301 - Pharmacy. The purpose of the discipline is to form in the student an understanding of the plant organism as a component of a living system, its variability, species diversity and role in biogeocenosis.
The objectives of the discipline are:
Acquisition of theoretical knowledge in the field of botany;
Formation of the ability to use modern technologies in the field of botany;
Acquisition of competencies necessary in the professional activities of a pharmacist;
Consolidation of theoretical knowledge in general biology.
To study a course in botany, you need knowledge gained from studying the disciplines of the humanitarian, social and economic cycle C1,
such as bioethics (C1.B.2) and Latin (C1.B.9), as well as disciplines of the mathematical and natural science cycle C2, such as biology (C2.B.8),
microbiology (C2.B.12).
Disciplines and practices for which mastering this discipline
(module) is necessary as the preceding:
Mastering the morphology and anatomy of plants is necessary for the study of medicinal plants in the course of pharmacognosy (C3.B.8).
In addition, knowledge of taxonomy, plant geography and plant ecology is necessary for completing field practice in botany
(C5.U), and educational practice in pharmacognosy (C5.U), production practice in pharmacognosy: “Procurement and receipt of medicinal raw materials” (C5.P).
Knowledge of cytology, plant histology, as well as plant histochemistry is necessary when studying medicinal products plant origin in the course of toxicological chemistry (C3.B.10), pharmacology
(C3.B.1), clinical pharmacology (C3.B.2), pharmacognosy (C3.B.8),
pharmaceutical chemistry (C3.B.9) and pharmaceutical technology (C3.B.6).
A specialist in his professional activities must be able to apply knowledge of the morphology and taxonomy of plants. Having completed the course in botany, the student should be able to perform macroscopic and microscopic analysis of plants. This requires knowledge of the morphology and anatomy of plants, knowledge of botanical terminology.
Studying the basics of plant physiology will help you understand the essence of the processes that lead to the formation of biologically active substances used in medical practice. Studying taxonomy will allow you to learn how to navigate the diversity of plants and identify medicinal plants from it.
As a result of mastering the discipline, the student must
Basic biological patterns of plant development and elements of plant morphology
Fundamentals of taxonomy of prokaryotes, fungi, lower and higher plants.
The main provisions of the doctrine of the cell and plant tissues, diagnostic signs plants used in determining raw materials.
Basic physiological processes occurring in the plant organism.
Fundamentals of plant ecology, phytocenology, plant geography.
Manifestations of the fundamental properties of living things at the main evolutionary levels of organization.
Work independently with botanical literature.
Work with a microscope and binoculars.
Prepare temporary microslides.
Carry out anatomical and morphological description and identification of the plant; work independently with the determinant.
Carry out a geobotanical description of phytocenoses, necessary for recording the stocks of medicinal plants.
Carry out herbarization of plants.
Botanical conceptual apparatus.
Technique of microscopy and histochemical analysis of micropreparations of plant objects.
skills in working with biological and polarizing microscopes.
Skills in making a preliminary diagnosis of the systematic position of a plant.
Skills in collecting plants and their herbarization.
Methods for describing phytocenoses and vegetation.
Plant research methods for the purpose of diagnosing medicinal plants and their impurities.
Using lecture course data in distance learning for students in a botany course allows you to:
The trainee must constantly monitor the current level of his knowledge and purposefully work to improve it; regularly on computer network communication, consult with the teacher on issues of interest; purposefully work on studying the discipline;
intensify the process of independent work on studying the discipline.
The teacher provides timely consultation to the student; in a timely manner
adjust the learning process by changing the algorithm of assignments, taking into account the individual characteristics and current level of knowledge of the student;
purposefully formulate plans for individual lessons with the student in personal contact.
The materials of the course of lectures on botany are compiled based on modern ideas about morphology, systematics and anatomy in world botany.
This edition includes the following sections:
History of the study of the flora of the Caucasus,
The role of botany in the life of the Pyatigorsk State Pharmaceutical Academy.
When preparing text fragments, the works were used as original materials by leading Russian botanists (A. L. Takhtadzhyan, T.
I. Serebryakova, V. Kh. Tutayuk, G. P. Yakovlev, M.A. Galkin, A.E. Vasiliev, A.G.
Elenevsky), as well as sources of literature from foreign experts (A. J.
Eames, L. G. McDaniels, K. Esau, P. Raven, R. Evert, R. Hine, D. Webb).
Translation of English-language publications was carried out directly by the authors of the work. Photographs and anatomical diagrams presented in the form of illustrations are either materials from the world's leading botanists, or with your own photographs authors (235 photographs).
B O T A N I K A
SUBJECT AND SECTIONS OF BOTANY
Botany is a branch of biology that deals with the study of plants, their form, structure, development, life activity, distribution, etc.
synthesized by host plants as a result of photosynthesis.
Currently, botany represents a combination of a number of interrelated sections.
Plant morphology - studies the external structure of plants, explores patterns and conditionality external form plants.
Plant anatomy - explores the peculiarities of the patterns of the internal structure of plants.
Plant cytology - studies the structure of plant cells.
Plant histochemistry - using microchemical reactions, identifies and studies substances found in the plant cell.
Plant embryology is a branch of botany that studies the patterns of the birth of an organism in the first stages of its development.
Plant physiology - studies the vital functions of plants: metabolism, growth, development, etc.
Plant biochemistry - studies the processes of chemical transformations of both chemical compounds that make up the body itself and substances
entering it from the environment.
Plant ecology - studies the relationship between plants and the environment.
Geography of plants - reveals patterns of distribution of plants in space.
Geobotany - studies the vegetation cover of the Earth.
Plant taxonomy - deals with the classification of plants and their
evolutionary development.
IN as applied botanical disciplines are
pharmacognosy - the study of medicinal plants, phytopathology -
the study of plant diseases, agrobiology - the study of cultivated plants.
History of botany
Botany is one of the oldest natural sciences. The initial knowledge of plants was associated with their use in the household and everyday life of people for food, clothing, and healing. Theophrastus (371-286 BC) is rightly called the father of botany. Theophrastus became the founder of botany as an independent science. Along with describing the use of plants in agriculture and medicine, he considered questions of a theoretical nature:
structure and physiological functions of the plant, geographical distribution, influence of soil and climatic conditions; tried to systematize plants. The role of a botany reformer was played by the great Swedish scientist C. Linnaeus (1707-1778), who created his famous plant reproductive system (1735). The milestone from which a new period in the development of botany began was the brilliant work of Charles Darwin
"On the Origin of Species" (1859). From this moment on, evolutionary teachings began to dominate in botany.
Domestic scientists made outstanding contributions to the development of botany.
The greatest creator of plant forms was I.V. Michurin. Among the first phytocenologists we name I.K.Pachossky, S.I.Korzhinsky, A.Ya.Gordyachin,
G.F. Morozova, V.K. Sukacheva. Classic works on elucidating the mechanism of photosynthesis belong to K.A. Timiryazev. The name of N.I. Vavilov, who formulated the law of homological series in hereditary variability, is inscribed in bright letters in the history of botany. A team of domestic botanists created a unique work “Flora of the USSR”.
History of the study of the flora of the Caucasus
The flora of the Caucasus has excited the minds of naturalists from time immemorial.
Many scientists from different European countries tried to get to this interesting region and describe the plants growing here. The very first mentions of the vegetation of the Caucasus and its species composition can be found in Tournefort. AND.
P. de (1656-1708) - a French botanist, was one of the first to make a clear distinction between the categories of genus and species, which paved the way for the systematic reforms undertaken in the 1730-1750s by Carl Linnaeus.
In his honor, Carl Linnaeus gave one of the genera of the Borage family
(Boraginaceae) name Tournefortia.
(1795-1855) - Russian taxonomist and botanist, was the director of the Imperial Botanical Garden in St. Petersburg. His most important works: "Verzeichnis der Pflanzen, welche wahrend der 1829-1830 unternommenen Reise im Kaukasus"(St. Petersburg, 1831), in which he first described the vegetation of the northern slope of Elbrus. He described a large number of new species and collected valuable herbarium material, which is stored in the Herbarium of the V.L. Komarov Botanical Institute in St. Petersburg.
F. K. Marshall von Bieberstein(1768-1826) - German botanist, author of a synopsis on the Tauro-Caucasian flora “Flora Taurico-Caucasica”. Plant genus Biebersteinia Steph. the geranium family (Geraniaceae) was named in honor of Bieberstein by the German botanist F. Stefani, in addition, there are a significant number of species bearing the name of the scientist: Bieberstein's bell (Campanula biebersteiniana C.A.Mey.), Bieberstein's peony
(Paeonia biebersteiniana Rupr.) .
H. H. Steven (1781-1863) - Russian botanist and entomologist, in 1812
organized the Nikitsky Botanical Garden in Crimea. The main works are devoted to the flora of the Crimea and the Caucasus, the taxonomy of seed plants and insects. A large number of species are named in his honor, including Papaver stevenianum Mikheev.
A.L. (1806-1893) - Swiss botanist and biogeographer.
Creator of the first code of botanical nomenclature " Prodromus Systematis Naturalis Regni Vegetabilis" Prodr. (DC.), described a large number of new species of various families, for example Corydalis caucasica DC.
R.E. Trautfetter (1809–1889) - director (1866-1875)
Imperial Botanical Garden. F.I. Ruprecht (1814-1870) - assistant director of the Imperial Botanical Garden (1851-1855). Ruprecht was sent to the Caucasus with the special purpose of studying the Dagestan flora.
The main work is Flora Caucasi (1867).
G.I. (1831-1903) - Russian geographer and naturalist, member-
Correspondent of the St. Petersburg Academy of Sciences. During expeditions to the Caucasus, he collected rich collection material. The volumes of "Museum caucasicum" published during Radde's lifetime were extensive,
beautifully illustrated publications. They were dedicated to zoology,
botany, geology and archeology of the Caucasus. The Radde birch tree is named after him
(Betula raddeana Trautv.) – endemic to the Caucasus, the bark of the trunk of this type of birch has a pinkish color, and the branches are dark brownish.
IN AND. -corresponding member Academy of Sciences of the USSR, director of the Odessa Botanical Garden. Described 40 new plant species of the Caucasus, for example,
MINISTRY OF EDUCATION AND SCIENCE OF THE REPUBLIC OF TATARSTAN
GOU SPO NABEREZHNOCHELNYSK COLLEGE OF ECONOMICS AND CONSTRUCTION
"BOTANY WITH THE BASICS
PLANT PHYSIOLOGY"
A SHORT COURSE IN DEFINITIONS AND TABLES
for part-time students
specialty 250203 “Gardening and landscape construction”
2008
Compiled in accordance with State requirements for the minimum content and level of training of college graduates in specialty 250203 “Lardening and landscape construction.”
A short course in botany is intended for part-time students of NESK in specialty 250203 “Landscape and landscape construction”. The manual was developed on the basis of the work program in the discipline “Botany with the basics of plant physiology” and is aimed at helping the part-time student in independent work. For ease of study, the main material is summarized, systematized and presented in the form of tables and basic definitions; The numbering of topics corresponds to the numbering of topics in the work program. In this manual, answers to control questions are not given in in full, independent additions by students on some topics are expected and do not replace topics studied in lectures.
Reviewed and approved I approve
cycle commission Deputy Director
construction disciplines in educational
work
N.P. Voronova N.P. Voronova
"____" ____________ 2008 "____" ____________ 2008
Compiled by: teacher of Naberezhnye Chelny
College of Economics and Construction
Ramazanova Yu.R.
Reviewer: Associate Professor of the Yerevan State Pedagogical University Zueva G.A.
INTRODUCTION
Botany is a science that studies the characteristics of the internal and external structure plants, their life activity, origin, distribution and relationship with each other and environment.
Plant physiology is a branch of botany that studies the functional activity of a plant organism.
Objectives of botany:
Morphology studies the patterns of the external structure of a plant, various modifications of organs in connection with the functions performed and environmental conditions; features of vegetative and seed propagation, growth and life expectancy.
Anatomy studies the internal structure of a plant. Data on the anatomical structure of plants are of great importance in identifying food products, animal feed, medicines, etc.
Systematics studies the diversity of the plant world, identifies related relationships between plants based on the similarity of external and internal structure, and arranges them into groups.
Objectives of plant physiology:
Study of the processes of growth and development, flowering and fruiting, soil and air nutrition, reproduction and interaction with the environment.
Learn to control the physiological processes occurring in the body of plants, create new, more effective forms of fertilizers, develop methods for increasing the productivity of agricultural plants.
1.1 Structure and physiology of a plant cell
A plant cell is a complex physiological system, which includes various organelles.
The function of a plant cell is the metabolism of substances by absorbing them from the environment, assimilation and release of decay products into the external environment.
Distinctive features of a plant cell:
tough cellulose cell wall.
The central vacuole is a container for cell sap.
plastids.
plasmodesmata in the pores of the cell membrane, through which the protoplasts of neighboring cells communicate.
reserve product – starch.
Organelle
Structure
Functions
Cell wall
The frame is formed by cellulose; in addition, it also contains mineral salts, lignin, suberin, and pigments.
Barrier. Frame.Water absorption. Maintains a consistent environment. Creates conditions for osmotic activity of roots.
Plasmalemma
Lipid bilayer with a lot of proteins.
Barrier. Biosynthesis.
Transport. Osmosis. Regulates metabolism with the environment. Receives irritation and hormonal stimuli.
Core
A spherical body with a double membrane, in which there are pores evenly distributed over the surface. Inside there is a matrix (nuclear juice) with chromosomes and a nucleolus.
Regulator of metabolism and all physiological processes. The nucleus communicates with other organelles through pores. Transfer body hereditary information.
Vacuole
A cavity bounded by a membrane. Contains juice, which includes various substances that are waste products (proteins, lipids, carbohydrates, tannins, etc.).
Stores proteins, carbohydrates, and harmful substances.
Supports turgor.
Endoplasmic reticulum ER
Rough
(granular
Smooth (agranular
A network of channels and extensions that extend into the vacuole.
Permeated with ribosomes.
Contains almost no ribosomes.
Center for membrane formation and growth. Transport. Connects all organelles with each other.
Synthesis, sorting and storage of proteins.
Synthesis of lipophilic substances: resins, essential oils.
Mitochondria
They consist of two membrane shells and a space between them. The inner shell forms outgrowths - cristae. The space between the cristae is filled with matrix.
They carry out the respiration process and synthesize ATP (adenosine triphosphoric acid - a source of energy).
Plastids:
Chloroplasts
Leukoplasts
Chromoplasts
They have a double shell and a main substance - stroma. Inner membrane in the form of bags. Contains green pigment chlorophyll.
The internal membrane system is poorly developed. Colorless (does not contain pigments).
They do not have an internal membrane.
Contains pigments – carotenoids.
Photosynthesis.
ATP synthesis.
Synthesis of fatty acids. Starch and proteins accumulate.
Not capable of photosynthesis.
Color flowers and fruits.
Functions of cytoplasmic membranes:
barrier – delimits cells and organelles from the external environment, controls the entry of various substances into the body;
transport - thanks to various carriers (ionic), selective transport of ions, proteins, carbohydrates into and out of the cell is carried out, structural - forms various organelles (vacuole, EPS, mitochondria, etc.);
receptor-regulatory - perceives and transmits chemical, physical (temperature, pressure) signals, providing adaptive responses of the cell.
Photosynthesis is the process of formation of organic substances using light energy in cells containing chlorophyll.
Influence of external factors on photosynthesis:
Light. In relation to light, all plants are divided into two groups: light-loving and shade-tolerant. Light-loving plants do not tolerate shading and grow in open places and only in the first upper tier of the forest (agricultural crops, plants of meadows, steppes, deserts, salt marshes; larch, pine, ash, aspen, birch, oak). Light-loving trees are distinguished by an openwork crown, rapid clearing of the trunk from branches, and early thinning of the tree stand. Shade-tolerant woody plants (spruce, fir, maple, elm, linden, rowan, hazel, buckthorn, euonymus) tolerate shading well and are found both in the upper and second tier. They are distinguished by a thick and dense crown with a large length along the height of the trunk, and slow clearing of branches. The leaves of light-loving plants have a thicker leaf blade, a large number of stomata and vascular bundles. The pigment content is less than that of shade-tolerant plants. More high content pigment ensures efficient photosynthesis under conditions of low light intensity and diffuse radiation.
Carbon dioxide concentration. CO2 is the main substrate of photosynthesis. Its content in the atmosphere largely determines the intensity of the process. The CO2 concentration in the atmosphere is 0.03%. At this concentration, the intensity of photosynthesis is only 50% of the maximum value, which is achieved at a content of 0.3% CO2. Therefore, in closed ground conditions, feeding the plant with CO2 is very effective.
Temperature. The effect of temperature on photosynthesis depends on the intensity of light. In low light conditions, photosynthesis is practically independent of temperature, as it is limited by light. For most plants, the optimal temperature is 20–30 °C. The minimum temperature for coniferous plants varies between -2 and -7 °C.
Water. The intensity of photosynthesis is favorably affected by a small water deficit (up to 5%) in leaf cells. However, with insufficient water supply, the intensity of photosynthesis decreases markedly. This is due to the closing of the stomata, as a result of which the delivery of CO2 to the leaf and the outflow of the resulting photosynthetic products from the leaf slow down.
Respiration is a complex process of obtaining energy by a cell, obtaining metabolites and their further use in synthesis; dissipation of energy in the form of heat. Energy is stored in ATP bonds.
Influence of external factors on breathing:
Water. With increasing water deficiency, growth is first suppressed, then photosynthesis and, lastly, respiration. If the intensity of photosynthesis decreases by 5 times, then the intensity of respiration decreases by approximately 2 times.
Temperature. The lower temperature limit of breathing lies well below 0°C. Respiration of fruit tree buds was observed at a temperature of -14 °C, pine needles up to -25 °C. A decrease in the respiratory activity of wintering parts of woody plants is associated with the transition of plants into a dormant state. The intensity of respiration increases rapidly as the temperature rises to 35-400C. A further increase in temperature leads to a decrease in respiration due to disruption of the structure of mitochondria and denaturation of enzyme proteins.
Aeration. Respiratory depression begins when the O2 content is less than 5%, in which case anaerobic respiration may begin. A similar phenomenon is observed with excessive waterlogging of the soil, flooding, and the formation of an ice crust. In such a situation, plants are severely depleted or even die due to energy deficiency, poisoning by accumulating ethyl alcohol, and also as a result of membrane damage. An increase in the concentration of CO2 as the final product of respiration leads to a decrease in the intensity of respiration, and an excessive increase in its concentration can cause tissue acidosis. For example, in storage facilities it is advisable to increase the concentration of CO2, which acts here as a narcotic drug. This helps to reduce the respiration rate of the fruit several times, facilitating their preservation for a longer time without loss of quality.
Fermentation is the oxygen-free breakdown of organic substances. Fermentation as a method of nutrition is common among bacteria.
Turgor is the elastic state of the shell caused by water pressure. Ensures that the succulent organs maintain their shape and position in space.
Osmosis is a selective unidirectional process of moving water through a membrane.
Plasmolysis is the loss of turgor by cells due to prolonged lack of water. In this case, the volume of the vacuole decreases and the protoplast is separated from the cell walls.
Deplasmolysis – disappearance of plasmolysis (restoration of turgor).
Cytorrhiz - with the loss of turgor in young tissues, protoplasts, contracting, do not separate from the cell walls, but pull them along with them and the tissue cells shrink.
Transpiration is the process of evaporation of water through stomata.
The influence of external conditions on transpiration:
Soil water. With a lack of water in the soil, the rate of transpiration of woody plants noticeably decreases. On flooded soil, this process, despite the abundance of water, is also reduced in trees by approximately 1.5-2 times, which is associated with poor aeration of root systems. Transpiration also decreases with strong cooling of the soil due to a decrease in the rate of water absorption. Lack or excess of water, salinity or cold soil affect the rate of transpiration through their influence on the absorption of water by root systems.
Air mode. Light increases the openness of stomata. The intensity of transpiration in diffused light increases by 30–40%. In the dark, plants transpirate tens of times less than in full sunlight. An increase in relative humidity leads to a sharp decrease in the intensity of transpiration of all rocks. As the air temperature rises, the leaves heat up and transpiration increases. The wind increases transpiration by carrying away water vapor from the leaves, creating undersaturation of air at their surface.
As the day progresses, the rate of transpiration changes. On a hot day, the water content of the leaves decreases compared to the norm to 25% or more. Daytime water deficit is observed at midday hours summer day. As a rule, it does not significantly disrupt the life of plants. Residual water deficit is observed at dawn and indicates that water reserves leaves recovered only partially overnight due to low soil moisture. In this case, the plants first wither severely, and then during prolonged drought they may die.
Guttation is the secretion of droplets of liquid by leaves at high air humidity, when transpiration is difficult. It provides a balance between water absorption and water consumption, causing the roots to intensively absorb water.
Mitosis is the basis of asexual reproduction. The process of cell division, as a result of which two daughter cells are formed from one mother cell, with the same set of chromosomes, which ensures the formation of genetically equivalent cells and maintains continuity in a number of cell generations.
Meiosis is the basis of sexual reproduction. A method of cell division with a halving of the number of chromosomes and the transition of cells from a diploid state (2n) to a haploid state (n), which ensures the preservation of a constant number of chromosomes in all generations and the diversity of the genetic composition of gametes, and therefore offspring during sexual reproduction.
1.2 Fabrics
Tissue is a complex of cells similar in origin, structure and adapted to perform one or more functions.
Fabrics
Structure
Functions
Educational
meristems
Cells that can divide repeatedly while maintaining this function.
They form new tissues and organs.
Integumentary
Epidermis
(skin)
Periderm
primary
Living cells lie very densely in several layers and do not contain chloroplasts. The outside is covered with cuticle. Cuticle wax can form outgrowths - scales. The stomatal apparatus consists of two guard cells, between which there is a gap. Trichomes are hair-like outgrowths of the outer cells of the epidermis.
secondary
Phellema (cork) - dead cells have secondary walls consisting of suberin and wax, the contents of the cells are filled with air.
Phellogen - cork cambium, consists of thin-walled living cells that can actively divide.
Phelloderm - consists of parenchyma cells.
Barrier.
Gives strength.
Regulation of gas exchange and transpiration.
Absorptive, excretory (glandular trichomes). Takes part in the synthesis of substances, in the movement of leaves, and perceives irritation. Reflects some of the sun's rays.
Barrier. Strength.
Protects against moisture loss and sudden temperature fluctuations.
Tissue formation.
Nourishes phellogen.
Mechanical
Collenchyma
Sclerenchyma
It consists of elongated living cells with unevenly thickened membranes.
Consists of dead cells with uniformly thickened walls.
Gives mechanical strength.
Conductive
Xylem
(wood)
Phloem
(bast)
The tracheid is a highly elongated cell with intact primary walls.
A vessel is a tube formed from many cells located one above the other. Openings appear between adjacent cells. Cells without contents. Wood fibers have thick shells.
Sieve elements: cells and tubes. The walls contain very small pores.
Companion cells, parenchyma cells and phloem fibers.
Conduct water with mineral salts dissolved in it.
Gives strength.
Conducted by assimilates.
They store nutrients and give strength.
excretory
Trichomes
Sunbirds
Milkies
Resin passages
External
Hairs are outgrowths of the epidermis in pelargonium, nettle, and currant.
They have a complex structure; are formed more often in flowers
Domestic
Living cells that accumulate latex in vacuoles in milkweed, celandine, and poppy.
Containers for citrus, coniferous, and umbelliferous fruits.
Protection from pests and microorganisms.
Revealing secrets.
They secrete nectar, carbohydrates, and essential oils.
Milky juice is secreted.
Essential oils.
Main
parenchyma
Chlorenchyma
Aerenchyma
Storage
Consists of round living cells containing chloroplasts and intercellular spaces.
The composition includes living parenchyma cells with very large intercellular spaces, mechanical, excretory and other elements.
Consists of living parenchyma cells.
Photosynthesis.
Breath.
Ventilation - oxygen enters the rhizomes, roots of marsh and aquatic plants.
They store water, proteins, lipids, carbohydrates, oils and resins.
2. MORPHOLOGY AND PHYSIOLOGY OF PLANTS
2.1 Root, root system
The root is an axial organ that has radial symmetry and grows in length due to the apical meristem. Morphologically, the root differs in that leaves never form on it and the apical meristem is covered by the root cap.
Root functions:
absorption of substances from the soil.
strengthens plants in the soil.
synthesis of various substances (hormones, amino acids).
deposition of nutrient reserves.
other functions: interaction of the root with the roots of other plants, microorganisms and fungi; organ of vegetative reproduction in some plants; monstera - breathing roots, banyan - stilted legs.
The root collar is the section of the border between the main root and the stem.
Root zones:
Division zone. It is located at the top of the root. The cells of this zone divide intensively. On the outside, its cells are covered with a root cap, which consists of living thin-walled cells that form abundant mucus, which reduces the friction of the root on soil particles and facilitates its advancement. The cells of the cap are continuously renewed.
Growth (stretch) zone. It is characterized by stretching of the formed cells, which causes the root to grow in length.
Suction (absorption) zone. It contains root hairs that absorb water and mineral salts from the soil. Root hairs are outgrowths of superficial root cells.
Conducting and strengthening area. Characterized by developed conductive tissues. The bulk of the lateral roots are located here, thanks to which a significant contact surface and strength of adhesion of the plant to the soil are provided.
Root system- the totality of all the roots of one plant.
Types of root systems:
Rod
fibrous
the main root is well defined, which forms the main core (pine, oak, camel thorn, sorrel, alfalfa)
there is no clearly defined main tap root; adventitious roots (cereals, bulbous plants) reach powerful development
Physiological role of nutrients
Battery
symbol
Physiological role
organogenic
Hydrogen
H
Component of organic matter and water.
Oxygen
O
Part of water and organic matter.
Carbon
C
Component of all organic substances.
macronutrients
Nitrogen
N
Part of proteins, enzymes, chlorophyll, ATP, vitamins.
Iron
Fe
It is part of many enzymes, participates in the synthesis of chlorophyll, in the processes of respiration and photosynthesis.
Potassium
K
Participates in the processes of photosynthesis, metabolism, formation and movement of sugars, improves water supply and reduces evaporation.
Calcium
Ca
It is part of the cell wall and plays a role in metabolic processes and in the formation of root hairs.
Magnesium
Mg
Component of chlorophyll.
Sulfur
S
It is part of proteins, enzymes, oils, vitamins, and promotes nitrogen fixation.
Phosphorus
P
It is part of compounds involved in various syntheses, respiration, growth and reproduction.
microelements
Bor
B
Affects growth processes, respiration processes, fertilization, stimulates the formation of nodules on the roots, the outflow of sugars into the fruits.
Cobalt
Co
Participates in fixation atmospheric nitrogen nodule bacteria.
Copper
Cu
Participates in the processes of photosynthesis, respiration, metabolism, regulates water balance
Molybdenum
Mo
Participates in the fixation of atmospheric nitrogen by nodule bacteria, in protein and carbohydrate metabolism.
Zinc
Zn
Component of some enzymes, involved in the synthesis of hormones and vitamins
2.2 Shoots and stems of plants
A shoot is a part of a stem that has grown in one growing season along with the leaves and buds located on it.
A node is where the leaves leave the stem.
An internode is a section of the stem between adjacent nodes.
Leaf axil is the angle between the leaf petiole and the stem.
Closed node - a leaf or whorl of leaves completely surrounds the stem with its bases.
Open node - bears a leaf that does not completely enclose the stem.
Elongated shoots have long internodes. They perform the function of supporting or skeletal organs.
Shortened shoots have very close internodes.
The main shoot is the first shoot of the plant that develops from the embryonic shoot.
Lateral shoots are second-order shoots that develop on the main shoot.
Annual shoots (growth) - grow from the buds in one growing season (once a year).
Elementary shoots are formed in one growth cycle, but there are several of them per year.
Escapes:
And a horse chestnut shoot without leaves: 1 apical bud; 2 axillary bud; 3 internode; 4 leaf tripe; 5 knot; 6th place of attachment of bud scales (limit of annual growth); 7 leaf traces (ends of torn conductive bundles); B elongated annual aspen shoot
Structure and types of kidneys
A bud is a shortened embryonic shoot that is in a state of relative dormancy.
Apical - (terminal) bud formed at the top of the shoot and causing the stem to grow in length.
Axillary buds - formed in the axil of the leaf and causing the development of lateral shoots. The bud consists of a stem with short internodes and rudimentary leaves or flowers. The top of the bud is covered with protective covering scales. The bud ensures long-term growth of the shoot and its branching, i.e. formation of a shoot system.
Vegetative buds - form shoots with leaves; floral (generative) - form flowers or inflorescences; mixed, (vegetative - generative) buds - form leafy shoots with flowers.
Overwintering (closed) or dormant buds have hard covering bud scales, which reduce evaporation from the surface of the internal parts of the buds, and also protect them from freezing, pecking by birds, etc.
Open buds are bare, devoid of scales.
Adventitious (adventitious) buds are formed on any plant organs and are no different in structure from others; they ensure active vegetative regeneration and reproduction of plants (raspberry, aspen, sow thistle, dandelion).
Stem
The stem is the main structural part of the shoot, consisting of nodes and internodes.
Functions:
conductive - ascending and descending currents of substances move between the roots and leaves in the stem.
mechanical - (support) carries leaves, buds, flowers and fruits.
assimilation - the green part of the stem is capable of performing the function of photosynthesis.
storage of nutrients and water.
Crowning is the formation of a crown by pruning.
Pinching is the removal of the upper part of a young shoot, as a result of which dormant buds located lower on the shoot begin to grow, increasing branching.
Pinching is the removal of side shoots or buds from plants that develop in the leaf axils, which is carried out as they appear in order to enhance the growth and development of large inflorescences (buds) on the main shoot.
Pinching - removal of the top of a growing shoot (when it reaches a length of 25 cm) with 2-3 undeveloped leaves. Regulate the growth of branches.
Metamorphoses of stems and shoots
Metamorphoses are modifications of organs with a change in form and function.
The spines of plants in hot, dry habitats can be of both stem and leaf origin. They perform two functions: they reduce the evaporating surface and protect against damage by animals. Spines of stem origin develop at the top of the stem, in the axils of the leaves, or are located on the stem node opposite the leaf (hawthorn, pear, thorn). If parts of the leaf are involved in the formation of the spine, then spiny teeth (thistles) are formed. Often the stipules (white acacia) or the entire leaf (cactus, barberry) are modified into a spine.
Phyllocladia Greek. phyllon leaf; klados branch are modified side shoots that take the form leaf blade and performing the function of photosynthesis (butcher's broom), in general, contribute to a decrease in the transpiration surface. On the shoots of butcher's broom, in the axils of the scaly leaves, leaf-shaped phyllocladia also develop, topographically corresponding to the whole axillary shoot and having limited growth. Leaf-shaped phyllocladies are also characteristic of species of the tropical genus Phyllanthus. Asparagus is characterized by small, sometimes needle-shaped phyllocladies, sitting in the axils of the scale-like leaves of the main skeletal shoot.
Tubers are highly thickened fleshy underground or aboveground shoots. In underground tubers, the leaves are reduced to small, early-falling scales, in the axils of which there are buds called eyes (potato tubers). Shoots develop from the buds. Aboveground tubers are formed due to the strong growth of the stem and bear normal leaves (kohlrabi cabbage).
Bulbs are modified shortened underground (less often aboveground) shoots. Underground bulbs of onions, garlic, wild onions. The lower part of the bulb, its dense base, is a shortened modified stem called the bottom. The bottom has a flat or cone-shaped shape. A large number of adventitious roots are formed in its lower part, and modified leaves (fleshy scales) are directed upward from it, storing water and nutrients. Outer dry or filmy scales are modified leaves that play a protective role, protecting the fleshy leaves from drying out.
Rhizome is an underground modified shoot that serves for vegetative propagation and for storing food. The rhizome ends in a bud, not a root cap. On the rhizomes, nodes are often clearly visible, on which scales and reduced leaves are formed. In the axils of the scales there are buds that give rise to above-ground and underground shoots, and adventitious roots are formed from the nodes.
Corms are modified, shortened, thickened stems like a tuber, having the appearance of a bulb (gladiolus, crocus). Unlike a bulb, a corm does not have juicy scales, so nutrients are concentrated in the stem part. The roots develop on the lower thickened part of the bottom, and in the upper part there is a central bud, from which a peduncle with leaves is formed. The outside of the corm is covered with dry films of leaves, in the axils of which there are buds.
Whiskers are creeping stems with long internodes (strawberry, stone fruit). Many climbing plants are characterized by the modification of leaves or parts, and sometimes entire shoots into tendrils, which have the ability to twist around a support during long apical growth. Their stem is usually thin and weak, unable to independently maintain a vertical position. In many legumes with pinnately compound leaves, the upper part of the leaf (rachis and several leaflets) is modified into tendrils. Very characteristic tendrils of leaf origin are formed in pumpkin plants. Tendrils of shoot origin can be observed in different types of grapes (wild and cultivated, passionflower and a number of other plants).
Life forms of plants
Life form, or biomorph, is the external appearance of plants, which arises in ontogenesis as a result of growth in certain environmental conditions and is adaptive in nature.
The trees have a well-defined lignified main trunk, which grows vertically more intensively than other shoots and persists throughout the life of the plant from several tens to several hundred and even thousands of years.
Shrubs the main trunk is absent or weakly expressed, branching begins almost at the very ground, so several more or less thin trunks are formed. As the main stem and the daughter stems closest to it die off in the center of the bush, new ones appear on the periphery. The life span of the shrub reaches several hundred years, but each stem lives 1040 years (yellow acacia, lilac up to 60 years). The height of the bushes does not exceed 46 m (barberry, cotoneaster, serviceberry, rose hips, currants).
Shrubs are characterized by the same branching pattern as shrubs, but they are shorter and have a shorter lifespan of skeletal axes of 510 years. Bilberry, lingonberry, blueberry, cranberry, heather, crowberry.
Subshrubs and subshrubs have shoots that in the lower part remain perennial and cork, while in the upper part they are annual and die or dry out in winter. The lifespan of their skeletal axes is 5–8 years. They are typical for desert and semi-desert areas (wormwood, solyanka).
Herbaceous plants are characterized by the fact that their stems do not become lignified and the above-ground parts, as a rule, die off by the end of the growing season. Herbs are annual, biennial and perennial.
Cushion plants have squat forms in the form of dense cushions. Shoots bearing leaves are perennial; shoots bearing flowers die off by winter. Cushion plants are characterized by inhibited growth of all shoots. They are confined to the most unfavorable habitats with low air and soil temperatures, with cold winds (tundra, highlands, deserts, rocks, screes), where free access to light suppresses the growth of shoots.
Succulents have succulent leaves and stems that contain a lot of water (sedum, sedum).
Lianas are forms that have a long stem (woody or herbaceous), which needs support to be held in an upright position (hops, bindweed, lemongrass, grapes).
Tillering types of cereals
Depending on the length of the underground part of the shoots and the direction of their growth, rhizomatous, densely bushy and loose-bush cereals are distinguished.
In rhizome grasses, extravaginal shoots form long branching rhizomes underground, from which leafy above-ground shoots arise, usually distant from each other (creeping wheatgrass). Long-rhizomatous, or scion-forming, grasses have long rhizomes. This feature of long-rhizome cereals is used when fixing sands (types of grate). Short-rhizome grasses, or bush grasses with short, hard-to-distinguish rhizomes (meadow fescue, sweet grass, cocksfoot, meadow timothy, etc.). Renewal buds of rhizomatous plants are formed in the previous autumn and, as a rule, overwinter in the soil at different depths, and in early spring above-ground shoots appear in these plants.
In loose bush grasses, the underground part of the extravaginal shoots is short, from 2 to 10 cm; the ends of the shoots, bending towards the soil surface, turn into above-ground shoots, forming a loose turf. Loose turf is a mother plant with sterile lateral shoots extending from it at some distance (meadow timothy).
In dense bush grasses, intravaginal renewal occurs, so a dense turf is formed, the side shoots grow vertically and are tightly pressed to the stem of the mother plant (turf grass).
2.3 Leaf
A leaf is a lateral organ of a plant of limited growth, growing at its base. Functions of leaves:
photosynthesis and transpiration;
gas exchange;
storing;
Main parts of the sheet:
The leaf blade - the main part of the leaf - is the main organ of photosynthesis.
The petiole serves to attach the leaf to the stem and for better positioning of the leaves in relation to the light, helping to weaken the impact of drops of rain, hail, and wind on the leaf blade. Participates in the movement of leaves.
The sheath is the expanded lower part of the leaf, which more or less covers the stem, protects the axillary buds and increases the strength of the stem when bending (in cereals, some umbellifers).
Stipules are paired lateral outgrowths at the base of the leaf of different shapes. They protect the young leaf in the bud.
Petiolate leaves with a petiole.
Sessile leaves with no petiole.
Simple leaves have one leaf blade, whole or sometimes strongly dissected.
Compound leaves consist of several leaf blades (leaflets) that are attached to the rachis (the common axis of a compound leaf) using their own petioles.
A simple apple leaf: 1 leaf blade; 2 petiole; 3 stipules; B compound rowan leaf
2.4 Flower
The flower is a shortened shoot of limited growth; generative organ of sexual reproduction.
Flower structure:
A, B diagrams of the flower structure: 1 receptacle; 2 sepals;
3 petals; 4 - stamens; 5 pestle
Bracts are covering leaves in the axils of which there is a flower.
Pedicel is the part of the stem under the flower.
Peduncle is the part of the stem that bears the inflorescence.
A sessile flower does not have a peduncle (flowers in the heads of some clovers, in aster baskets).
The receptacle is the upper, expanded part of the peduncle and serves to attach all other parts of the flower.
The calyx consists of green free or fused sepals.
The corolla is composed of free or fused colored different colors petals. The calyx and corolla make up the perianth, or integument, of the flower. The perianth protects the flower itself (stamens and pistils) from external adverse influences and attracts pollinating insects.
A simple perianth is formed only by a calyx (ozika, nettle, sorrel, male flowers of oak, elm) or only by a corolla (tulip, lily, lily of the valley, scilla).
The double perianth consists of a calyx and a corolla (apple tree, gravilate, mock orange, lilac).
Coverless (naked) flowers (willow, ash, poplar) do not have a perianth.
The stamen consists of a filament and an anther; sessile anthers without a filament are rarely formed (magnolia) or the anthers are underdeveloped. Pollen is formed in the anthers, which is used for pollination.
The pistil is formed as a result of the fusion of one or more carpels. Each pistil contains an ovary, a style and a stigma.
The ovary is the lower expanded part of the pistil. The stigma of the pistil is adapted to catch and retain pollen. Ovules (ovules) are formed inside the ovary.
Nectaries are special glands that secrete a sugary liquid - nectar.
Flowering - opening of the anthers and functioning of the stigmas of the pistils.
Pollination is the transfer of pollen from the anthers of the stamens to the stigmas of the pistils.
In self-pollination, pollen is transferred on the stigma of the pistil within a given flower or individual. Self-pollination is considered as a phenomenon caused by unfavorable environmental conditions, i.e. unfavorable for cross-pollination; it plays an insuring role. Self-pollination occurs more often in annuals with a short life cycle, growing in unfavorable environmental conditions on dry and poor soils (shepherd's purse, rough clover, crowded clover). This type of pollination allows them to quickly restore the population of the species.
Cross pollination is the main type of pollination in flowering plants. It is biologically more perfect.
Biotic pollination:
Entomophily: pollination by insects. Insects visit flowers to collect pollen, nectar, and sometimes in search of shelter, laying eggs, and searching for a partner. The flowers attract insects with their scent. The aroma of essential oil is not always pleasant. The smell of rotting meat is emitted by the flowers of rafflesia, slipweeds, and some kirkazons. This aroma attracts flies as a place to lay eggs.
Ornithophily, pollination by birds, is a phenomenon characteristic of the tropics. Eucalyptus, cannas, aloe, acacia, some cacti, and fuchsias are pollinated by birds (hummingbirds, sunbirds, and florets). The flowers of these plants are odorless, but brightly colored, secreting a lot of watery nectar.
Chiropterophily, pollinated by bats, is common in the tropics of Asia and America. They pollinate plants such as banana, agave, and baobab. The flowers are greenish-yellow, brown or purple in color, which is better perceived by bats at night. In addition, these flowers have strong “landing grounds”, thick pedicels, strong leafless sections of branches, and a musty smell that imitates the smell of bats themselves.
Abiotic pollination:
Anemophily pollination by wind. Wind-pollinated plants bloom before the leaves bloom (hazel, birch), their flowers are without perianths, without smell and color of the petals (inconspicuous), but with large feathery stigmas. The flowers are collected in inflorescences (catkin, raceme, spike). Stamens hanging freely.
Hydrophily is the transfer of pollen by water or on a water surface. This pollination is characteristic of a few aquatic plants (Vallisneria, Elodea, etc.). In Vallisneria, pollination occurs on the surface of the water. The pollinated female flower then goes under water again.
Fertilization is the fusion of two gamete sex cells (male and female), resulting in the formation of a new zygote cell, from which the embryo of a new organism develops.
2.5 Seed. Fetus
A fruit is an organ that develops from the ovary after fertilization. Protects seeds and promotes their distribution.
After the fertilization process, the ovule (ovule) turns into a seed.
Bean seed:
and the general view; b embryo; 1 spine; 2 seed entrance; 3 scar; 4 seed suture; 5 kidney; 6 stems; 7 cotyledons
The seed is the reproductive organ of all seed-bearing plants.
The seed coat is a modified covering of the ovule. It protects seeds from drying out, premature germination, and possible mechanical damage.
The seed embryo usually develops from a fertilized egg. The embryo consists of a root, always facing the spermatic opening, a rudimentary stalk (subcotyl, or hypocotyl), cotyledons of the first leaves of the embryo and a bud. The bud consists of a growth cone and leaf primordia.
Endosperm is a tissue that stores nutrients necessary for the development of the embryo.
Techniques for accelerating seed germination
Soaking seeds in water at a temperature of 25300C for 2448 hours, depending on the density of the seed shells. Sprout in bowls on gauze, cotton wool, napkin, adding water just above the level of the seeds. Containers with seeds are covered with film or glass. The swollen seeds are slightly dried and sown immediately.
Stratification - keeping seeds for some time at low temperature (050C) in a moist substrate (sand, peat, moss). In autumn, the seeds are mixed with sand 1:3, the mixture is poured into boxes. Store at +50C. In the spring, before sowing, the seeds are separated from the sand through a sieve.
Scarification is mechanical damage to thick and hard seed shells.
Treatment of seeds with hot water 80850C for 24 hours.
Soaking seeds in solutions of chemicals. Carry out to soften the hard covers of seeds or stimulate growth.
2.6 Plant growth and development
Growth is the process of new formation of structural elements of the body, which is accompanied by an increase in mass and size.
Development is qualitative changes in the structure and functional activity of the plant and its parts during development.
Growth phases:
Embryonic phase - growth occurs due to the division of meristematic cells. Requires large amounts of nutrients and energy.
Stretch phase - cells increase in size, vacuoles appear in them, which subsequently merge into one large one.
Differentiation phase - the final formation of the cell occurs, its transformation into a specialized cell (conducting, mechanical, etc.) with the dominance of the corresponding structures or organelles.
Stationary phase – the number of cells and their biomass changes slightly.
The degradation phase is cell death.
Ontogenesis is the individual development of an organism from the moment of formation of the zygote until death.
Stages of plant development
The embryonic period in seed plants lasts from the moment of formation of the embryo (seed) until the beginning of seed germination. In vegetatively propagated plants - from the moment of bud formation in the organs of vegetative propagation until the beginning of their germination. Growth processes are in the latent phase.
Juvenile period of initiation of growth and development of vegetative organs from the germination of a seed or vegetative bud to the appearance of the ability to form reproductive organs. Plants increase in size, growth processes predominate.
Maturity is the period from the appearance of the first rudiments of the reproductive organs to the formation of buds, bulbization. Growth processes are combined with the formation of flowers, and the vegetative organs of plants continue to grow.
Reproduction – fruiting, development of fruit, seeds, tubers. The processes of formation of flowers, seeds, tubers, and bulbs predominate.
Old age - from complete cessation of fruiting to natural death. Growth is sparse (stump shoots, fattening shoots).
Physiological role of growth regulators
№
Name of hormonopod. substances
Place of synthesis
Physiological role
Strengthens
Suppresses
Growth stimulants
1
auxin
the escape
growth of shoots in length, lateral and adventitious roots, development of seedless fruits
growth of side shoots
participates in plant movement
2
gibberellin
sheet
stimulates flowering, accelerates fruit ripening and seed germination, stem growth in length
3
cytokinins
root
growth of roots in length, lateral shoots, development of seedless fruits
lateral root growth
4
brassins
in all tissues
resistance to adverse conditions
root growth
Growth inhibitors
5
abscisic acid
in all tissues
transition to bud dormancy, leaf fall during drought, fruit ripening
transpiration, because closes stomata
6
ethylene
in all tissues
tissue aging, fruit ripening, leaf fall
cell division
Influence of external factors on growth:
Temperature. The optimal temperature is the temperature at which growth is fastest. Depending on their adaptability to temperature, plants are distinguished between heat-loving and cold-resistant. For plants in the temperate zone, the minimum temperature is 510°C, the optimal is 25-30°C, the maximum is 40-45°C. In heat-loving crops, all cardinal points are shifted towards higher temperatures. The optimal temperature is different not only for different plants, but also for different organs. Root growth usually occurs at lower temperatures than growth of the above-ground parts of the plant.
Light. The plant can grow in both light and darkness. In complete darkness, the growth pattern changes: etiolation occurs. As a result of strong stretching of the cells, plants have long internodes, and the leaf blades are underdeveloped and yellowish in color due to the lack of chlorophyll.
Water mode. Soil and atmospheric humidity affects the water content of plant tissues and plant growth. With a lack of water, plants grow stunted. Roots can grow only when there is sufficient soil moisture; in dry soil, their growth is impossible. The growth of above-ground parts is less dependent on air humidity, since the growing points are protected from direct contact with the dry atmosphere.
Mineral nutrition. For normal growth it is necessary to supply plants with all the necessary minerals.
Air. The oxygen content in the soil is much lower than in the atmosphere. On average, the optimal oxygen concentration for root growth is 8-10%; reducing it to 2-3% leads to inhibition of root growth.
Tropisms are growth movements of plants caused by unilaterally acting factors.
Phototropism is the bending of a plant towards a light source.
Chemotropism is the movement of plants under the influence of chemical compounds.
Geotropism is bending caused by gravity.
Hydrotropism is movements caused by the uneven distribution of moisture in the soil.
Thermotropism is movements associated with temperature fluctuations.
Nastia are growth movements that occur under the influence of diffuse factors that do not have a strict direction (light, temperature, etc.): the opening and closing of flowers during the change of day and night.
Photoperiodism is a natural change in day length throughout the year.
The photoperiodic response is the body’s physiological response to changes in day length.
Vernalization - (T.D. Lysenko) stimulation of flowering by low positive temperatures of winter grains, biennials and many perennial plants. Cold helps wintering plants transition from growing to flowering.
2.7 Plant propagation
Reproduction is a process that leads to an increase in the number of individuals.
Vegetative propagation is the propagation of plants by parts of vegetative organs while preserving the characteristics and properties of a given variety. Vegetative propagation is used in cases where plants do not retain the characteristics of the variety when propagated by seed (tulip, rose, gladiolus) and when plants do not form viable seeds (many tropical and subtropical species).
Wheatgrass, lily of the valley, iris, phlox, and chrysanthemum reproduce by rhizomes. When the old section of the branched rhizome dies, its young sections with adventitious roots, buds and above-ground shoots become independent plants.
Dividing the bush. The bush of the plant is dug up, shaken off the ground, cut with a knife or carefully torn apart. Each separated part (division) must have at least two or three shoots or buds and a root system. Old and diseased roots are cut out, and the above-ground part is shortened by 20-30 cm in order to reduce water evaporation. To prevent the roots from drying out, the cutting, cleared of old shoots, is immediately planted in a previously prepared place, at the same depth at which the plants grew before.
Propagation by tubers (dahlias, begonias, buttercups, anemones). In winter, the aboveground part of the plants dies, and in the spring new shoots form from the dormant buds of the tubers. The tubers are pre-germinated. As soon as the buds (eyes) are clearly identified, the tubers are cut with a sharp knife so that each separated part has part of the root collar and 12 buds. The sections are sprinkled with crushed charcoal. The separated tubers prepared for planting are laid out in a well-ventilated room at a temperature of 20-22°C and left for two days. Under such conditions, the sections are covered with a protective layer of tissue and the risk of rotting is reduced.
Reproduction by corms. Every year, dying, the old corm forms one or two new daughter corms. Between the old and new corms, small corms are formed, covered with a dense shell on top. Children are used for reproduction. If few children are formed, then large corms can be cut vertically into several parts so that each has at least one bud and part of the bottom. The sections must be sprinkled with charcoal and dried. Then the divisions are planted to a depth of 8–10 cm.
Propagation by bulbs. Membranous bulbs have tulip, narcissus, hyacinth, etc. Such bulbs are covered on the outside with dry covering scales (films). Thanks to these scales, the bulbs do not dry out and are better stored. In the axils of the scales there are buds. From the buds, children are formed, which these plants reproduce. The bulbs of lilies and hazel grouse do not have dry films, and the juicy scales are loosely arranged, dry out easily and are poorly stored. Such bulbs are called scaly. For their reproduction, along with the children, you can use separate scales, which when favorable conditions babies form new bulbs.
Reproduction by layering. Layerings are rooted shoots separated from the mother plant. After separation they become independent plants. Horizontal layering is obtained by placing annual shoots in shallow (2-5 cm) grooves, which are secured in several places with wooden or metal pins, and covered on top with a layer of light earth, the thickness of which should be 15-2 cm. During the summer, growing shoots are hilled 2-4 times. A year later in the spring, the cuttings are dug up, divided and planted. Lilacs, clematis, roses, etc. are propagated in this way. Arc-shaped layering is planted in the spring. At a distance of 15-20 cm from the bush, pin the middle of the branch, sprinkle it with a layer of earth, and tie the top to a peg. The ditch is covered with light, damp soil. In the autumn or spring of next year, the cuttings are separated from the mother plant and transplanted to a permanent place. Shrubs (quince, currant, lilac), as well as peonies, are propagated by vertical layering. The mother plant is pruned short in the spring to allow new shoots to actively grow. During the summer, the bush is covered several times with nutritious soil and watered as the shoots grow. By autumn, most of the shoots give roots, they are unplanted and separated from the mother plant.
Root shoots (raspberry, cherry, cherry plum, apple tree) are shoots developed from adventitious root buds.
Cutting is a part of a stem (with two or three buds), root or leaf, separated from the mother plant, which, under favorable conditions, forms new roots and develops into an independent plant, retaining all the properties and characteristics of the mother plant. The average length of the cutting is 8-10cm. The cuttings are cut with one or two nodes. In plants with alternate leaves, the lower cut is made 2-3mm below the bud, at an angle of 45-50° to the shoot axis. In plants with opposite and whorled leaves, cuts are made at right angles to the shoot: the lower cut is under the node, and the upper cut is made 5 mm above the bud.
A stem cutting is a part of a stem with leaves or buds.
Green cuttings are usually harvested in the first half of summer and have immature wood. The cuts on the cuttings should be even. To reduce evaporation, the lower leaves on the cuttings are removed, the remaining leaves, except small ones, are shortened by about 1/31/2 of the length.
Semi-lignified cuttings are harvested in the second half of summer from shoots whose growth has already slowed down. Semi-lignified cuttings have leaves and not fully ripened wood (roses, most ornamental shrubs, indoor evergreens (ivy, ficus). The length of cuttings with two or three eyes is 10-15 cm. The lower leaves are removed, the upper ones are shortened. Cuttings are cut in the same way as and when harvesting green cuttings.
When rooting green and semi-lignified cuttings, growth stimulants are often used, which contribute to the development of a more powerful root system. The prepared cuttings are tied into bunches, immersed in a solution of one of the preparations (10,500 mg of the preparation per 1 liter of water) to a depth of 2–3 cm and kept in it (green for 3–6 hours, semi-lignified for 8–24 hours) at a temperature of 20–23°C in a shaded room. After treatment, the cuttings are washed in water and planted in boxes, pots, greenhouse soil or on ridges in open ground. Concentrations of drugs for different crops are not the same.
As a substrate for rooting cuttings, you can use coarse sand, a mixture of sand and peat in equal parts, or a mixture of perlite and peat in equal parts. Green cuttings are planted in the substrate to a depth of 0.5-1cm, semi-lignified cuttings to a depth of 2-3cm. The planted cuttings are covered with film or glass frames to create high air humidity (85-100%). Before rooting, the plants are protected from direct sunlight, the substrate is sprayed and moistened several times a day. The air temperature should be approximately 20-21 °C, and for heat-loving plants 22-24 °C. When the cuttings take root, they are planted in a permanent place.
Lignified cuttings are harvested in autumn or spring, when the plant is dormant. They are cut off from annual shoots (woody shrubs: rose, mock orange, spirea, hydrangea). The cuttings are cut 25-30cm long with three to five buds and planted at an angle of 60-70° on beds in open ground so that one or two buds remain above the ground. The plantings are watered abundantly and mulched with a layer of peat 2–3 cm thick. By autumn, roots grow on the cuttings and they are transplanted to a permanent place.
A leaf cutting is a leaf or part of a leaf used for vegetative propagation of ornamental herbaceous plants (sansevieria, echeveria, gloxinia, Uzambara violet, begonia), as well as some open ground crops (lily, phlox, sedum). The substrates and rooting conditions for leaf cuttings are the same as for green stem cuttings.
From well-developed mother plants, cut a leaf with a small part of the petiole 2-4 cm long, plant it in damp sand obliquely, leaving the leaf on the surface, and cover it with glass or film. Complete rooting occurs in approximately 20-25 days. During this period, the plants are transplanted to a permanent place.
Reproduction by vaccinations.
Grafting is the artificial merging of a cutting or bud of one plant with another plant that has roots.
Scion is a plant, part of which is grafted onto another (rootstock) to give it new properties.
The rootstock is the plant onto which the scion is grafted.
The rootstock has roots, with the help of which it supplies the scion with water and dissolved nutrients from the soil. The scion provides the entire plant with organic substances formed during photosynthesis.
the rootstock and scion must be compatible, i.e. belong to closely related botanical species or genera.
plants for grafting must be healthy;
The grafting operation should be carried out in dry, warm weather, in the spring, before the start of sap flow (when the buds have not started to grow) or in the second half of summer.
Tree and fruit crops (lilac, rose, azalea, citrus, etc.) are propagated by grafting. Grafting is used in cases where it is necessary to obtain varieties that, when propagated by seed, do not retain their decorative qualities and are difficult to take root when cutting or dividing a bush. Grafted plants usually flower better, are resistant to diseases and pests, and are well adapted to local weather conditions due to the rootstock of a local species. Using grafting, it is possible to obtain various decorative forms of plants (weeping, dwarf, etc.), and it is also possible to reduce the time of crop cultivation (by grafting low-growing varieties onto vigorous rootstocks).
Budding is grafting with a bud and a small piece of bark. The eyes (buds) are cut from the middle part of the annual shoots of the scion with a sharp knife with a thin layer of wood 22.5 cm long. On the rootstock on the north side, use a sharp knife to cut the bark in the shape of the letter “T”. Using the “bone” of a special budding knife, the bark is slightly separated from the wood and the peephole is inserted into the cut. Then the edges of the bark are pressed and the grafting site is tightly tied with plastic wrap as close to the bud as possible, leaving it free. If the grafting is done correctly, then after two to three weeks the rootstock will grow together with the scion and a shoot will gradually develop from the grafted bud. After this, the rootstock above the grafting site is cut off and the plant is grown for two to three years.
Copulation is grafting with cuttings. Make oblique cuts on the rootstock and scion with a sharp knife and place them on top of each other so that they coincide. The grafting site is tightly tied with plastic tape. If the grafting is done correctly, the rootstock will fuse with the scion and the buds of the scion will begin to grow.
Clouding is grafting by proximity.
With all grafting methods, the grafting site is tightly tied, and the cuts are coated with garden pitch.
3. PLANT SYSTEMATICS
Systematics is a branch of botany dealing with the scientific classification of plants.
The Code of International Botanical Nomenclature is a set of rules governing the establishment and use of names for living and fossil plants and fungi.
General system of organisms
A. Superkingdom Prenuclear organisms:
1. Subkingdom Bacteria
2. Subkingdom Blue-green algae
B. Overkingdom Nuclear organisms:
1. Animal Kingdom
2. Kingdom Mushrooms:
a) Sub-kingdom Lower mushrooms
b) Sub-kingdom Higher mushrooms
3. Kingdom of Plants
a) Sub-kingdom of Bagryanka
b) Sub-kingdom True algae
c) Subkingdom Higher plants
Species – a biologically isolated set of individuals, clones, freely interbreeding and producing fertile offspring; possessing a number of common morphological and physiological characteristics.
Comparative characteristics of organisms
3.1 Bacteria
Characteristic
1
Organization
Unicellular, less often colonial and filamentous;
2
Spreading
Everywhere.
3
Structure
The shell is of a protein nature without cellulose and chitin; capable of mucus. There is no formed nucleus with a nuclear membrane, and the role of the organ of transmission of hereditary information and the regulator of all processes in the body is performed by the nucleoid. There are no mitochondria, plastids, ER, Golgi apparatus. There are vacuoles, some have bacteriochlorophyll.
5
Reproduction
They reproduce vegetatively or by budding, asexually (spores), and sexually.
6
Spore
A bacterial cell that has lost water shrinks and becomes covered with a dense membrane to withstand unfavorable environmental conditions.
7
Movement
Fixed and mobile, moving with a sliding movement or with the help of flagella
8
Relation to O2
Aerobes - most develop with sufficient oxygen content or with a slight lack of it. Anaerobes - in the complete absence of oxygen (few).
Bacterial plant diseases
Name of the disease
Signs of the disease
Bacteriosis
Yellow spots appear on the edges of the lower leaves, quickly increasing in size and turning brown. The tissue surrounding the spots turns yellow. Small elongated dark brown watery spots or stripes appear on the stems. On the affected nodes, the spots become dark, weeping and covered with sticky droplets of grayish-white or yellowish color and dry out. Small, slightly depressed spots or brown ulcers form on root crops; the tissue in the affected areas rots and emits an unpleasant odor.
Bacterial cancer
Tears in the form of dark stripes appear on the stems. Light spots with darkening in the center form on the fruits. Ulcers appear on the stalks, petioles, leaf veins and shoots. Gradually, over 30-60 days, the plants wither and dry out.
3.2 Algae
Characteristic
Features of the structure and functioning of the body
1
Form
Unicellular, colonial or multicellular
2
Spreading
Those living in water are divided into: phytobenthos - algae that attach to the bottom of a reservoir or to underwater objects;
phytoplankton - most float freely in the thickness or are suspended. Some algae live on trees, soil, and soil.
3
Cell structure
The cell membrane consists of cellulose and pectin substances; often contains iron, lime carbonate; often covered with mucus. There can be one or many nuclei. Chromatophore - plastid - organelle of photosynthesis contains chlorophyll and other pigments
4
Body structure
Thallus (thallus) – not divided into organs and tissues
Amoeboids - lack a hard cell membrane and are able to move like amoebas;
Filamentous - cells are connected into simple or branched threads;
Lamellar - in the form of plates, one-, two- and multi-layer;
Siphonal (non-cellular) - do not have cellular partitions in the thallus if present large number cores;
Charophytic - multicellular thalli consist of a central axial thread on which “whorls of leaves” sit (articulated structure)
5
Nutrition
The autotrophic method of nutrition is the main one; phototrophs. Heterotrophic in some algae, perhaps. mixed – auto – heterotrophic.
6
Reproduction
By budding, filament breaking, spores or sexual intercourse
7
Spore
Mobile or immobile cell specialized for reproduction
8
Movement
Fixed, movable
9
Relation to O2
Aerobes - most develop with sufficient oxygen content or with a slight lack of it.
3.3 Fungi mushrooms
Characteristic
1
Form
Multicellular, unicellular.
2
Spreading
Land dwellers, some live in water
3
Cell structure
The cell membrane is dense, in lower animals it consists of pectin substances; in the higher ones from cellulose and chitin - impenetrable, durable; M.B. colored with pigments. There may be one or many nuclei, but no plastids. There is glycogen - a reserve nutrient. The cytoplasm contains ER, ribosomes, mitochondria, and the Golgi apparatus.
4
Body structure
Mycelium is a vegetative body in the form of a system of thin colorless threads (hyphae)
Lower fungi have non-cellular mycelium, hyphae without partitions in the form of a single dissected multinucleated cell or in the form of a naked lump of cytoplasm without a shell
Higher - hyphae are divided by septa into segments
6
Reproduction
By budding, fragments of mycelium, spores or sexually
7
Spore
A cell specialized for reproduction
8
Relation to O2
Aerobes - most develop with sufficient oxygen content or with a slight lack of it. There are anaerobes.
Fungal plant diseases
Name of the disease
Signs of the disease
Powdery mildew
It affects the ends of young shoots, leaves, inflorescences and fruits. A white or slightly reddish powdery coating appears on the affected parts of the plant. Over time, the coating on the shoots becomes grayish or brown, similar to felt. It is covered with a large number of fruiting bodies in the form of black dots. The affected shoots are stunted in growth, their tops dry out, the leaves harden, curl and die, and the ovaries fall off.
Rust
Yellow, somewhat convex spots appear on the leaves. After 2-3 weeks, rusty-brown pads appear on the underside of the leaves. Deep gray cankers with a reddish border form on the stems. Then the leaves fall off, the stems become brittle and lose their frost resistance.
Gray rot
A gray fluffy coating appears on the surface of diseased fruits, producing dust when touched. Brownish spots appear on the stalks, enveloping them in a ring, which causes the death of the green ovaries. The berries dry out, turn into gray lumps and remain on the bush for a long time.
Alternaria blight
Affects buds, leaves and stems. Round or elongated ash-gray spots appear on the leaves along the main vein. The affected buds do not bloom and dry out or bloom one-sidedly. An olive-black velvety coating appears in the affected areas. The tissue on the stems dies, leading to the death of the plant.
Fusarium (jaundice)
Affected leaves become yellow-green in color. Fine dark mottling appears on them. Diseased leaves turn brown, curl, and droop. Dark stripes and cracks form on the stems, and a pink coating may appear at the base of the stems - sporulation of the fungus.
3.4 Lichenophyta
Characteristic
Features of the structure and functioning of the body
1
Form
Multicellular
2
Spreading
Widely distributed in the tundra and forest-tundra. They are the first to settle in places where other plants cannot grow.
3
Body structure
Thallus is a body in the form of intertwining fungal hyphae with algae, not divided into organs. The crustal layers are formed by a denser plexus of hyphae. In the core layer, the hyphae are intertwined more loosely. Algae are distributed evenly between the hyphae or confined to a specific layer. The following morphological types of lichens are distinguished:
Scale - in the form of a crust, tightly merging with the substrate (stone, tree bark) - goldenrod
Leafy - in the form of incised lobes, weakly attached to the substrate - xanthorium
Bush-like - in the form of branching stems, weakly attached to the substrate - bearded lichen
4
Nutrition
Symbiosis is the mutually beneficial coexistence of a fungus with algae or bacteria. The mycelium receives mineral elements and water from the soil. Algae form carbohydrates through the process of photosynthesis. The bacterium is capable of assimilating atmospheric nitrogen.
5
Reproduction
Fragments of the thallus or special organs - soredia
6
Soredia
A small number of algal cells entwined with fungal hyphae.
3.5 Bryophyta
Characteristic
Features of the structure and functioning of the body
1
Form
Small perennial, less often annual multicellular, higher plants are the most simply arranged.
2
Spreading
They are found on all continents, but more of them are found in areas with a temperate and cold climate in the Northern Hemisphere, in damp places.
3
Body structure
Thallous or leafy. There are no roots. The function of roots is performed by rhizoids - colorless outgrowths similar to root hairs or water is absorbed by the lower parts of the stem.
4
Nutrition
Autotrophs (photosynthesis)
5
Reproduction
By fragments of the thallus, brood buds, spores or sexually.
3.6 Fern-like Polypodiophyta
Characteristic
Features of the structure and functioning of the body
1
Life form
Perennial herbaceous rhizomatous plants, there are tree-like, liana-like and epiphytes.
2
Spreading
They are found on all continents, but most of them are in tropical and subtropical regions, in damp places.
3
Body structure
Leafy: the aboveground stem is not developed in herbaceous ferns (except tree ferns); they have an underground shoot - a rhizome, from which adventitious roots extend. Leaves - fronds - grow almost unlimitedly at their apex. The leaf blade is pinnate and performs the functions of photosynthesis and reproduction.
4
Nutrition
Autotrophs (photosynthesis)
5
Reproduction
Asexual (spores) and sexual. Spore germination requires heat, light and water.
Characteristic
Features of the structure and functioning of the body
1
Life form
Mostly trees, less often shrubs, tree-like vines and epiphytes. There are no herbs. Most are evergreens.
2
Spreading
Found on all continents.
3
Body structure
The main root system is maintained throughout life. Most have needle-shaped leaves (needles), some are large, similar to the leaves of ferns or palm trees. Wood consists almost entirely of tracheids, there are no vessels - excl. oppressive.
4
Nutrition
Autotrophs (photosynthesis)
5
Reproduction
Seeds. They do not form fruits. Vegetative propagation by cuttings, grafting.
6
Seed
Seeds are formed from ovules located openly at the ends of the shoots. Seeds contain an embryo with cotyledon leaves and an endosperm (nutrient reserve), which has a haploid set of chromosomes and is formed before the embryo.
3.8 Angiosperms Magnoliophyta
Characteristic
Features of the structure and functioning of the body
1
Life form
Perennial and annual herbaceous plants, trees and shrubs, vines and epiphytes.
2
Spreading
Found on all continents, there are aquatic, amphibious, marsh plants, dry and mountainous places habitats.
3
Body structure
In addition to tracheids, wood contains vessels; instead of sieve cells, sieve tubes with companion cells appeared. A flower is a reproductive organ.
5
Reproduction
They reproduce by seeds and (or) vegetatively. They form fruits that develop from the ovary of a flower. Double fertilization is typical.
6
Seed
Seeds are formed from ovules located in the ovary of the pistil of a flower. The endosperm is of triploid origin and is formed simultaneously with the formation of the embryo.
Distinctive features of mono- and dicotyledonous plants
Signs
Monocots
Dicotyledons
Root system
Fibrous - consists of adventitious roots, the main root dies early.
Taproot - well developed main root
Stem
Herbaceous, incapable of secondary thickening, branches rarely. Vascular bundles without cambium are scattered throughout the stem
Herbaceous or woody, capable of secondary thickening, branching. Conducting bundles with a cambium are located in one large mass in the center of the stem or have the appearance of a ring
Leaves
Simple, entire, usually without petiole and stipules, often with a sheath, parallel or arcuate venation. The leaves are arranged in two rows
Simple or compound, the edges are dissected or jagged, often with petiole, stipules, reticulate or palmate venation. The arrangement of leaves is alternate, opposite
Flower
Three-membered, less often two- or four-membered
Five-, less often four-membered
Pollination
Most plants are wind pollinated
Most plants are pollinated by insects
4. GEOGRAPHY, PLANT ECOLOGY AND PHYTOCOENOLOGY
Plant geography studies the patterns and reasons for the distribution of plants on the globe and identifies the boundaries of their distribution.
Ecology studies the relationship between plants and the environment, the influence of various factors on plants.
Geobotany studies the composition, structure, development and distribution of plant communities, their use and transformation possibilities.
Flora is a historically established set of plant species growing in a certain area. Each continent or region has its own flora, i.e. a collection of families, genera and species of plants. They are combined into phytocenoses - natural communities.
Vegetation – (vegetation cover) the entire set of plant communities of any territory.
Phytocenosis is a collection of plants on a homogeneous territory (plant community), characterized by a certain composition, composition and relationships between plants and the environment. The boundaries of communities are unclear and one community gradually passes into another. Each phytocenosis is part of an ecosystem, which is a unity of living and nonliving components.
Area – part earth's surface or water area within which a particular species occurs.
Forms and types of habitats:
Continuous (closed) - known locations are more or less evenly distributed over the entire area of distribution of the species.
1) encircling - stretched along the landmass of the globe in latitude.
2) circumpolar - cover the polar northern edge of the land in a ring.
3) meridional – areas elongated in the meridional direction.
4) radiate and fringed - irregular, asymmetrical in shape with numerous protrusions, habitats in different directions (actively spreading species).
The torn area breaks up into several relatively independent, isolated parts.
Floristic zoning of land is a division of land based on the characteristics of the flora of different territories. The basic unit of regionalization is the kingdom, which is characterized by a certain set of endemic families. Kingdoms, according to the degree of reduction in the rank of endemics, are in turn divided into sub-kingdoms, regions and provinces.
Kingdoms
Distribution area
Flora composition
I. Holarctic
(3 sub-kingdoms, 9 regions)
Occupies more than half of all land, covering the entire extratropical part of the northern hemisphere
More than 30 endemic (ginkgo, sycamore, etc.) and typical families (willow, birch, walnut, beech, laurel, pine, magnolia, ranunculaceae, etc.)
II. Paleotropical (5 subkingdoms, 12 regions)
Covers the tropics of the old world, excl. Australia
40 endemic families: banana, pandanus, nepenthes, up to 300 species of palms, nutmeg, cloves, figs.
III. Neotropical (5 regions)
Includes central and tropical South America
25 endemic families (bromeliads, cocaceae); typical cacti, palm trees, cinchona, agaves, hevea, chocolate tree
IV. Cape
(1 area)
Located in southern Africa
More than 7,000 plant species (endemic - 7 families and 210 genera). Silver, rhino, iron and yellow trees
V. Australian (3 regions)
Australia
Characterized by a high percentage (86%) of endemism: brunoniaceae, Davidsoniaceae, acacias and eucalyptus are typical.
VI. Holantarctic
(4 areas)
Patagonia, Tierra del Fuego, New Zealand, subantarctic islands
Relatively poor in species; 10 endemic families.
Relicts (from Latin - remnant) are species or communities of plants preserved from extinct, once widespread floras: tall juniper, wild pistachio, Crimean cistus, butcher's broom, dwarf birch, polar willow, lingonberry, wild rosemary.
Endemics are plants with an extremely narrow range and limited in their distribution to a particular region or country (ginkgo, Welwitschia).
Plant ecology
The biosphere is a part of the Earth’s shell inhabited by living organisms.
An ecosystem is a section of the biosphere of various sizes. An established stable community of living and nonliving components, within which an almost independent, self-regulating circulation of substances and energy occurs.
The natural environment is a set of elements of living and inanimate nature in which organisms, populations and natural communities exist.
Ecological factors are individual environmental factors that have a direct or indirect impact on the properties and state of communities and individual organisms.
Three groups of environmental factors:
abiotic factors (factors of inanimate nature);
biotic factors, relationships between individuals in a population and between populations in a natural community;
anthropogenic factors - human activities leading to changes in the habitat of living organisms.
Optimum is the intensity of the factor that is most favorable for the life of the body. The limits beyond which the existence of an organism is impossible are called the lower and upper limits of endurance.
Tolerance means the endurance of a species in relation to fluctuations in any environmental factor. If the value of any factor goes beyond the limits of endurance, then such a factor is called limiting.
A limiting factor is an environmental factor (light, temperature, soil, nutrients, etc.), which, under a certain set of environmental conditions, limits any manifestation of the vital activity of organisms. For example, some plants need less zinc if they are grown in shade rather than full sun; This means that the concentration of zinc in the soil is less likely to be limiting for plants in the shade than in the light.
Abiotic environmental factors:
Climatic (light, temperature, humidity, precipitation, wind, pressure, etc.),
Edaphic (soil),
Hydrographic, or factors of the aquatic environment.
Orographic - relief.
Light serves as the main source of energy for all life processes occurring on Earth. Solar radiation determines the heat balance of the biosphere. In addition to solar radiation, the climate of the zone is influenced by atmospheric circulation, relief, etc. The existence of large zonal types of vegetation (tundra, taiga, steppes, deserts, savannas, tropical rainforests, etc.) is mainly due to climatic reasons.
Temperature important factor, affecting growth, development, reproduction, respiration, synthesis of organic substances and other vital processes for organisms. For most terrestrial organisms the temperature optimum ranges from 1530°C. In the active state, they do not tolerate negative temperatures. The upper temperature limit for most is 4045°C.
Edaphic factors are a set of physical and chemical properties of soils that can have an environmental impact on living organisms. The composition and diversity of plants is influenced by the following soil properties: structure and composition, pH acidity, the presence of certain chemical elements, etc.
Biotic environmental factors:
Intraspecific – interactions between organisms of the same species
Interspecific – interactions with other species of plants, microorganisms, animals.
Intraspecific interactions
Competition is an interaction that boils down to the fact that one organism consumes a resource (water, minerals, light, space, air), which would be available to another organism and could be consumed by it. When competition occurs, one living creature deprives another of part of the resource. Intraspecific competition is the most severe, since plants of the same species require the same living conditions: certain temperature air and soil, amount of water, a certain amount and ratio of macro- and microelements
Plant communities
Phytocenosis (plant community) is a historically established collection of different plant species in a homogeneous area of territory. Characterized by certain relationships with each other and with environmental conditions.
Each plant community has a certain structure: selection of species (floristic composition), horizontal and vertical distribution (layering).
The floristic composition of the community depends on the biological and ecological characteristics of the plant species. Species composition determines the specificity and appearance of the phytocenosis. Types of phytocenosis can be represented by different life forms. This ensures the fullest use of nutrients and energy by the community.
Dominant – a plant species that occurs in large numbers and occupies a large area; plays a leading role in the community.
Aboveground layering is the arrangement of plants at different heights due to different needs for lighting conditions. There are 7 tiers in mixed forests.
The underground organs of plants - roots, bulbs, rhizomes and tubers - are also arranged in tiers. And this allows plants to absorb minerals and water from different layers of the soil. The underground layering is “mirrored aboveground”: the roots of tall trees penetrate deepest, and the roots of herbaceous plants, seedlings, and mycorrhiza penetrate closer to the surface. The top layer is a special layer – the forest floor.
Dynamics of plant communities
Plant communities are characterized by relative stability over time. As a result of the influence of natural or anthropogenic factors, phytocenoses change.
Seasonal (cyclical) changes are repeated from year to year due to changes in plant growth conditions throughout the year.
Fluctuations – year-to-year changes are associated with unequal meteorological and hydrological conditions, as well as with the life characteristics of certain plant species.
Secular (succession) – a gradual change of phytocenosis to another is possible as a result of the influence of natural or anthropogenic factors.
Zonal vegetation
Zonal vegetation - has its own characteristic features that distinguish the plant communities of this zone from the phytocenoses of other zones.
Tundra zone
Climate
The soil
Vegetation
Characterized by negative average annual temperatures, summers are short (23 months), cool, and frosts are possible in all months of the growing season. The amount of precipitation prevails over the amount of evaporation, and plants develop in conditions of excess moisture. There is little precipitation (400 mm per year), but at low temperatures the amount of evaporation is less than the amount of precipitation. Snow cover is insignificant: in European tundras about 50 cm, in Yakutia about 25 cm. Strong winds often blow, blowing away thin snow cover and causing deep freezing of the soil. In summer there is a polar day in the tundra.
The soils are very cold, in summer at a shallow depth the t-soil is 10°C, and permafrost occurs at a depth of 1.5–2 m.
Characterized by the absence of trees, the predominance of mosses and lichens, shrubs and shrubs. Plant communities are low-tiered (1-3 tiers). The first tier consists of shrubs (ledum, blueberry, blue willow), the second shrubs (dryad) and grasses (alpine foxtail, arctic bluegrass, viviparous knotweed), the third mosses and lichens. Characteristic tundra vegetation is short (15-20cm). Dwarf, rosette, and cushion life forms of plants are common. There are almost no annuals. The roots hardly go deep into the soil, being located near the surface.
Subzone
Vegetation
arctic tundra
The vegetation cover is not continuous; about 60% of the area is occupied by vegetation. The species composition is very poor. Dryads predominate. The grass cover contains many sedges, cotton grass, grasses, and polar poppies. There are many lichens, especially crustose lichens, inhabiting stones and rocks.
Moss-lichen
The soil is completely covered with mosses and lichens, among which there are some herbaceous plants.
Shrub tundra
Characterized by a closed vegetation cover of shrubs and shrubs
Forest-tundra
Against the background of a closed, low-growing vegetation cover, there are isolated oppressed trees (species of birch, spruce, larch).
Forest zone
Climate
The soil
Vegetation
From moderate continental in the European part of Russia to sharply continental in Eastern Siberia and monsoon in the Far East. The average July temperature is from 14 to 19.5 °C. Winter is relatively cold, with persistent severe frosts; in the middle zone of the Non-Black Earth Region there are frequent thaws in winter. The annual precipitation is 600-700 mm, the total amount exceeds the amount of evaporation, so the plants are in conditions of sufficient moisture. In summer, plants receive relatively a lot of heat and moisture, which favors their growth and development.
podzolic and soddy-podzolic soils, often with signs of waterlogging. Under broad-leaved forests in the south and west of the forest zone there are gray forest soils.
They have a complex tiered structure. The tree layer is the dominant element of the forest. Trees of smaller height and growing trees form the understory; the next shrub tier is multi-tiered; herbaceous or herbaceous-shrub and moss-lichen tiers are also often multi-tiered.
Subzone
Vegetation
Coniferous forests
The dominant species can be trees of one type (spruce forests, pine forests), or two types - spruce-pine forests, spruce-fir forests, etc. But no more than three tree species. There are shrubs: blueberries, lingonberries, bearberries, northern linnaea, cranberries, wild rosemary, etc. grow in wetlands. Among the herbs, there are species of clubmosses, bileaf moss, European rosemary, various types of wintergreens, etc.
Mixed forests
The dominant broad-leaved trees are pedunculate oak, sycamore maple and small-leaved linden. The undergrowth is dominated by common hazel shrubs. In the herbaceous-shrub layer there are many representatives of spruce forests: European rosewort, two-leafed grass, common sorrel, etc., and representatives of broad-leaved trees: lungwort, hairy sedge, yellow green grass. The moss cover is developed mainly in the form of spots.
Broadleaf forests
Zonal vegetation is represented by oak forests. English oak, small-leaved linden, sycamore maple, tall ash; elm, elm, and field maple are less common. The shrub layer is dominated by common hazel, euonymus species, mountain ash, honeysuckle, and buckthorn. Herbs: common sedge, hairy sedge, lily of the valley, rosemary, European hoofed grass, obscure lungwort, corydalis, amazing violet, peach-leaf bell. There are many ephemeroids: anemone, Siberian scilla, snowdrop, spring clear. There is almost no moss.
Steppe zone
Climate
The soil
Vegetation
Continental climate with hot, dry summers and cold winters with stable snow cover. The amount of precipitation (300500 mm) is less than the amount of evaporation, so in the steppes plants are in conditions of lack of moisture. Maximum precipitation in the form of showers occurs in mid-summer, during the hot period. Plants do not have time to absorb moisture, and it quickly evaporates. Winds blow almost constantly, sometimes dry winds blow.
Chernozems of various types.
When moving from north to south in the steppes of the European part, the following patterns are observed: 1) the grass stand becomes increasingly sparse; 2) the colorfulness of the steppes is declining, the number of dicotyledons in the floristic list is decreasing; 3) in the north, perennials predominate, to the south the role of annuals increases and the number of narrow-leaved grasses increases; 4) the species composition is depleted.
Subzone
Vegetation
Meadow
steppes (forest-steppe zone)
Characterized by alternating oak forests and steppe vegetation, forest areas are found along ravines and depressions, in conditions of high humidity. The humidity is higher than in other subzones, the grass cover is higher (up to 1 m) with a predominance of forbs from meadowsweet, sage, broad-leaved grasses grow: pubescent grass, middle wheatgrass. There are quite a few narrow-leaved grasses of feather grass and fescue.
Forb-fescue-feather grass
It is characterized by an increasing role of narrow-leaved turf grasses and greater drought resistance of plants. Among the forbs there are prickly sage and drooping sage.
Fescue-feather grass steppes
They are distinguished by very sparse and low grass stand (up to 40cm). Narrow-leaved turfgrass fescue, Lessing's feather grass, and annual ephemerals predominate here; some ephemeroids; of the life forms, “tumbleweeds” (tumbleweeds) predominate. The species composition of the grass stand is poor.
Desert zone
Climate
The soil
Vegetation
Sharply continental. Characterized by high fluctuations in annual and daily temperatures. July temperature is 25°C, in winter temperatures are below zero. Summers are long and hot, winters are frosty and covered with snow. In summer, the soil surface heats up to 60–70°C. The annual precipitation amount is no more than 200-300 mm, and the amount of evaporation is several times higher than the annual precipitation amount. Plants experience an extremely acute lack of moisture. Dry and gusty winds often blow.
The soils are more or less saline. Gray soils and gray-brown desert soils are typical
Two main groups of life forms: xerophytic plants, adapted to endure unfavorable conditions (subshrubs and perennial grasses), ephemerals - intolerant of drought and managing to finish the growing season before it begins. The dominant subshrubs are wormwood and goosefoot. Camel thorn blooms in the midst of the heat, its roots go deep groundwater, 1015 m deep.
Typically, in desert plants, the underground part is much larger than the above-ground part.
Subzone
Vegetation
Semi-deserts
Phytocenoses are formed by species of steppe and desert vegetation. Desert subshrubs grow on drier soils, and turfy narrow-leaved steppe grasses grow in microdepressions on wetter soils. The subzone is a motley mosaic of alternating steppe and desert vegetation.
Northern clay deserts
They are characterized by sparse vegetation cover with a predominance of semi-shrubs of wormwood and goosefoot plants called “hodgepodges”: gray quinoa, salt marsh anabasis, leafless anabasis. Northern clayey deserts are also called wormwood-hodgepodge deserts due to the nature of their vegetation.
Southern clay deserts
Low-growing ephemeroids, bulbous bluegrass, and short-columnar sedge dominate.
Control questions
Respiration of tubers, corms, bulbs, seeds and conditions for their storage.
The role of soil microorganisms in the mineral nutrition of plants.
Wilting of plants due to lack of moisture.
Drought resistance of plants.
Seed germination and conditions necessary for this process.
Methods of dispersal of seeds and fruits.
Chemical methods for regulating plant growth.
Plant resistance to unfavorable environmental conditions.
Frost, heat and salt tolerance of plants.
The role of bacteria in nature and human life.
Green and brown algae, their economic importance.
The role of lichens in nature and economic activity person.
The importance of mosses in nature.
Ferns used for landscaping populated areas and interiors.
The role of angiosperms in nature, significance for humans and animals.
The role of humans in the distribution of plants on the earth's surface.
Literature
Biology: Reference. materials: Textbook. manual for students / Ed. DI. Traitaka
Bobyleva O.N. Open ground floriculture: Textbook. manual for 10-11 grades - M. Academy, 2004.
Botany: textbook for students. education institutions prof. education / (A.S. Rodionova and others). - M.: Publishing Center "Academy", 2006.
Botany with basics of ecology: Textbook. manual for pedagogical students. Institute for specialties No. 2121 “Pedagogy and methods of beginning. training"/L. V. Kudryashov, M. A. Gulenkova, V. N. Kozlova, G. B. Rodionova. M.: Education, 1979.
Vronsky V.A. Applied ecology: textbook. Rostov n/d.: Publishing house “Phoenix”, 1996.
Dolgacheva V.S. Botany: textbook. aid for students higher ped. textbook establishments / V.S. Dolgacheva, E.M. Aleksakhina. -2nd ed., erased. – M.: Publishing Center “Academy”, 2006.
Kuznetsov V.V. Physiology of plants: Textbook. for universities / Vl. V. Kuznetsoa, G.A. Dmitrieva. –M.: Higher. school, 2005.
Lemeza N.A., L.V. Kamlyuk, N.D. Lisov Biology in exam questions and answers. 2nd ed., rev. and additional – M.: Rolf, Iris-press, 1998.
13 EMBED CorelDraw.Graphic.8 1415
The course "Botany" for undergraduate students of the Faculty of Agriculture is taught in the first and second semester. Weekly load - 1 hour of lectures per week and 1 hour of laboratory classes. At the end of the second semester there is an exam.
You will need a sketchbook for class. We will make all drawings in pencil; no colored pencils, felt-tip pens, etc. are allowed. At the lecture, accordingly, you will need a thicker notebook, because there is a lot of material.
During laboratory classes we will write tests. Preparation questions will be posted here in advance. The test is graded. At the end of the semester, based on the test results, the student may be exempt from taking the exam if the grades are above a C, or not allowed to take the exam if the grades are below a C!
Lectures are given by candidate of biological sciences, associate professor Elena Konstantinovna Krutova
Lecture No. 1. Botany as a science. Main branches of botany. Objects studied by botany.
1. Botany as a science. Definition of botany. Meaning.
2. Main branches of botany:
* Plant histology
*Plant morphology
* Plant anatomy
* Plant taxonomy
*Plant Physiology
* Plant Embryology
* Phytocenology
* Plant ecology
* Geography of plants
* Paleobotany
3. Objects of botany. System of living Takhtadzhyan (1973). The place of plants among living organisms. The cosmic role of plants - they convert the energy of sunlight into energy chemical bonds, i.e. into organic matter. Thanks to photosynthesis, people have gas, oil and coal, and therefore gasoline, etc. Plants carry out the primary synthesis of carbohydrates. This means that they synthesize glucose from inorganic substances - carbon dioxide and water. Plants are at the base of all ecological pyramids. In short, all the energy we have is solar, but we can use it thanks to plants.
4. Difference between plants and animals and fungi.
* Type of nutrition (autotrophic/heterotrophic/mixotrophic)
* Difference on cellular level
* Plastids
* Vacuoles with cell sap
* Features of the structure of the cell wall
* Cellular center
* The concept of protoplast (Kelliker, 1862)
* Parenchymal and prosenchymal forms of cells (Link, 1807)
* Basic organelles of a plant cell
* Method of absorption of substances
* Growth features
*Body surface area
*Essential storage nutrient
* In what form do they absorb nitrogen?
* Meiosis in the life cycle
Lecture No. 2. The structure of a plant cell.
1. Cell wall
Primary
Secondary
2. Structure of cell wall pores
3. Cell wall growth
4. The main organelles of a plant cell
Membrane
Mitochondria
Plastids
EPR
AG
Lysosomes
Non-membrane
5. Structure of plastids and their function
6. Vacuole, composition of cell sap
7. Inclusions
Lecture No. 3. Plant tissues (histology)
1. What is fabric? Features of plant tissues. Complex and simple fabrics. Living and dead.
2. Classification of plant tissues
* Educational fabrics
Cell structure and totipotency
Functions and concept of cell differentiation
Classification by origin
Primary
Secondary
Classification by location
Apical or apical
Lateral or lateral
Intercalary or intercalary
Wound meristems. Callus.
* Integumentary tissues
Primary integumentary tissues
Epidermis
Epiblema
Secondary integumentary tissues
Periderm or plug
Crust
* Ground tissue or parenchyma
Assimilation parenchyma or chlorenchyma
Storage parenchyma
Absorbing parenchyma
Aquifer parenchyma
Airborne parenchyma
* Mechanical fabrics
Sclerenchyma
Bast fibers
Wood fibers
Sclereids
Collenchyma
Lamellar
Corner
* Conductive fabrics
Phloem
Xylem
Conductive bundles
* Excretory tissues
Endocrine
Exocrine
Lecture No. 4. Vegetative organs of plants, roots.
1) Vegetative and generative organs.
1.1. Vegetative – root, stem, leaf
1.2. Generative – flower, fruit, inflorescence, etc.
2) Features inherent in plant organs - polarity, symmetry, tropism, growth characteristics.
3) Root. Signs of the root. Functions of the root.
4) Classification of roots by shape
5) Classification in relation to the substrate
6) Classification by origin - main, lateral, subordinate
7) Root system
8) Classification of root systems by origin and form
9) Zones of the root tip - root cap, division zone, extension zone (growth zone), absorption zones, conduction zone.
10) The structure of the root in the division zone is the cone of root growth (dermatogen, pleroma, periblema).
11) Root structure in the suction zone (primary root structure)
11.1. Epiblema and mechanism of root absorption of water and minerals
11.2. Primary cortex - exoderm (thickened walls, protective function), mesoderm (absorbing parenchyma), endoderm (dead in one row, Casparian belts, passage cells).
11.3. Central cylinder – pericycle (primary lateral meristem), radial vascular bundle (diarchic, tetrarchic, etc.)
12) Transition to the secondary structure of the root
12.1. Where does the cambium begin to form?
12.2. Solid ring of cambium, cambium of heterogeneous origin (from cells of thin-walled parenchyma and from the pericycle)
12.3. The cambium is divided unevenly (parenchymal origin - conducting tissues, pericyclic - parenchyma of the medullary, or radial, rays)
12.4. Formation of phellogen and desquamation of the primary cortex
Lecture No. 5. Root metamorphosis.
1. The concept of metamorphosis
2. Root metamorphosis
2.1. Storage roots - root crops and root tubers - what is the difference between one and the other?
2.2. Mycorrhiza
2.3. Nodules
2.4. Contractile roots
2.5. Board-shaped roots
2.6. Columnar
2.7. Stilates and breathing
Lecture No. 6. Stem.
1 Stem as shoot axis
2. Signs of the stem and functions. The escape.
3. Morphological structure of the shoot - node, internode, axil, metamera
4. Classification of shoots - by direction of growth, by the length of internodes, by the location of shoots in space
5. Morphological classification of life forms of plants according to I.G. Serebryakov (woody, semi-woody, herbs, vines)
6. Bud - embryonic shoot. Structure and classification of buds by composition, location on the stem, presence of protective scales, and condition.
7.Leaf arrangement
8.Growth and branching
9 Anatomy of the stem
Growth cone – tunic and body, location of meristems in the stem
Procambium and cambium
The primary structure of the stem is bunched, continuous
10.Stem of corn and rye - bunched primary structure of the stem
11.Secondary structure of the stem of dicotyledons - continuous (non-beamed), bunched, transitional
12. Stem of flax, firewood, sunflower, woody stem linden trees
Lecture No. 7. Leaf.
1. Definition and characteristics of a leaf
2.Sheet functions.
3. Parts of a leaf - leaf blade, petiole, stipules, sheath, ligule, ears, bell.
4. Classification of leaves.
Simple and complex
According to the shape of the leaf blade
According to the shape of the edge of the leaf blade
According to the shape of the base of the leaf blade
5. Leaf Formations
6. Heterophylly
7. Leaf venation
8. Anatomical structure of the dorsoventral leaf
9. Anatomy of the isolateral leaf
10. Anatomical features of pine needles
Lecture No. 8. Metamorphosis of leaf and shoot.
1. What are metamorphoses and modifications of plant organs
2. Similar and homologous organs
3. Leaf metamorphosis
Fleshy leaves (aloe, sedum, agave)
Tendrils (fence pea, leafless china, Djungarian clematis)
Thorns (cactus, robinia, euphorbia, flute acacia)
Phyllodes (Australian acacias)
Trapping devices (sundew, pitcher plant, bladderwort)
4. Metamorphoses of the shoot
Fleshy stems (cactus)
Tendrils (watermelon, grapes, passionflower)
Thorns (thorn, plum, pear, hawthorn)
Cladodes and phyllocladies (Mühlenbeckia, Zygocactus, butcher's broom)
Rhizome
Long rhizomes (wheatgrass, pigweed, coltsfoot)
Short-rhizome plants (iris, kupena, bergenia)
Stolon
Tuber
Aboveground tubers (kohlrabi, orchids)
Rhizomatous tubers (colocasia = taro)
Tubers on stolons (potatoes, nightshade, Jerusalem artichoke, Japanese chist)
Bulb
Imbricate (lily)
Tunicata (onion, hyacinth)
Semi-tunicate (scilla)
Corm (gladiolus)
Kochan (white cabbage)
Lecture No. 9. Plant propagation.
1. What is reproduction
2. Types of reproduction
3. Vegetative propagation of plants
Natural
Artificial (cuttings, grafting, layering, clonal micropropagation)
4. Actually asexual reproduction
What is a spore
Place of meiosis in the plant life cycle
Sporophyte
Sporangia
Sporogenesis
Equisporous
Diversity
5. Sexual reproduction
The essence of the sexual process
Gametes, fertilization, zygote
Types of sexual process
Isogamy,
Heterogamy
Oogamy
Hologamy
Conjugation
Plant reproductive organs
6. Alternation of generations and change of nuclear phases
Lecture No. 10. Plant taxonomy.
1. History of taxonomy
2. Taxa
3. Nomenclature
4. Phylogenetic systems
5. The Kingdom of Prokaryotes
6. Kingdom of Drobyanka
Dept. Archaebacteria
Dept. Eubacteria
Dept. Cyanobacteria
7. Features of representatives of the Cyanobacteria department
8. Distribution and importance of cyanobacteria
9. Kingdom of Eukaryotes
general characteristics
10. Kingdom of Plants
general characteristics
11. Subkingdom Lower plants
Difference between inferior and superior
Transcript
1 M.E. PAVL'S BOTANY. LECTURE NOTES Textbook For first-year students studying in the specialty "Landscape Architecture" Moscow Peoples' Friendship University of Russia 2013
2 UDC 58(07) BBK 28.5я73 P 12 Approved by the RIS Academic Council of the Peoples' Friendship University of Russia Reviewers: Doctor of Biological Sciences, Professor S.V. Goryunova, Candidate of Biological Sciences I.I. Istomina Pavlova, M. E. P 12 Botany. Lecture notes [Text]: textbook / M. E. Pavlova. M.: RUDN University, p. ISBN Study guide “Botany. Lecture notes" prepared at the Department of Botany, Plant Physiology and Agricultural Biotechnology Faculty of Agriculture RUDN University and is intended for first-year students studying in the specialty “Landscape Architecture”. The manual contains basic information on the course of botany, necessary for the formation in students of holistic ideas about the structure, diversity, planetary role of plants and their use by humans, as well as for further study special disciplines. ISBN UDC 58(07) BBK 28.5ya73 Pavlova M.E., 2013 Peoples' Friendship University of Russia, Publishing house, 2013
3 Lectures 1 INTRODUCTION TO THE COURSE OF BOTANY. SECTIONS OF BOTANY. IMPORTANCE OF PLANTS. PLANT AS AN INTEGRAL ORGANISM The goal of our short botany course is to briefly familiarize students with the structure and diversity of plants. Garden and park construction specialists and landscape architects need this knowledge for the correct use of plants in the design of artificial landscapes. AB specifically requires knowledge of the biology of plants, the requirements for their living conditions, in order to correctly place them, create the necessary conditions for them (soil composition, lighting), and provide appropriate care. With this approach, plants will thank people with their beautiful and healthy appearance, rapid growth, and abundant flowering. Botany as a science was formed more than 2000 years ago. Its founders were the outstanding figures of the ancient world, Aristotle (BC) and Theophrastus (BC). They summarized the accumulated information about the diversity of plants and their properties, cultivation techniques, propagation and use, and geographic distribution. Nowadays, botany is a multidisciplinary science. Its general task is to study individual plants and their aggregates of plant communities. Botanists study the structure and development of plants in ontogenesis, the relationship of plants with the environment, patterns of distribution and distribution of individual species and all plant cover on the globe; 3
4 the origin and evolution of the plant kingdom, its diversity and classification; reserves in nature of economically valuable plants and their paths rational use, are developing the scientific basis for introducing into culture (introduction) new fodder, medicinal, fruit, vegetable, industrial, and ornamental plants. Sections of botany. Botany, as part of the more general science of biology, in turn, is divided into a number of special sciences, the tasks of which include the study of certain patterns of the structure and life of plants or vegetation. Morphology is one of the largest and earliest formed sections of botany. This is the science of the patterns of emergence and development of various life forms of plants and their individual organs. The origin and development of plant organs are considered both during the individual development of an individual from seed germination to the end of life (ontogenesis), and during historical development(evolution) of the entire species or any other systematic group to which a given individual belongs (phylogeny). In the process of development of morphology, even more specialized sciences emerged in its depths: cytology (regularities of the structure and development of the basic structural unit of plants, the cell); histology, or anatomy (the origin, development and structure of various tissues that form organs); embryology (patterns of development and structure of the embryo); organography (establishment, development and structure of plant organs); palynology (pollen and spore structure). Florography. The task of this science is to recognize and describe species. Species described by florographers are divided into groups by taxonomists based on similarities that reflect relatedness. 4
5 Systematics is the science of the diversity of species and the causes of this diversity. The task of taxonomy is to bring all our knowledge about the species described by florographers into an easily visible scientific system. Based on a whole series of methods, a taxonomist unites related species into systematic groups of higher rank, genera, families, etc. Plant geography (phytogeography) is the largest branch of botany, the main task of which is to study the patterns of distribution and distribution of plants and their communities (cenoses) in land and in water. Ecology. Plant life depends on the environment (climate, soil, etc.), but plants, in turn, influence the creation of this environment, taking part in the soil-forming process, changing the climate. The task of ecology is the study of the structure and life of plants in connection with the environment. This science is of paramount importance for practical agriculture. Plant physiology is the science of the life processes of plants, mainly about metabolism, movement, growth, developmental rhythms, reproduction, etc. Microbiology is the science of the features of life processes occurring in microscopic organisms, the predominant part of which are bacteria and some fungi. The successes of soil microbiology are widely used in agricultural practice. Paleobotany is the study of fossil plants from past geological periods. Other branches of botany have become so isolated in connection with the solution of special problems and the methods of work used that they have long constituted special sciences, including biophysics, biochemistry, radiobiology, genetics, etc. The importance of plants in the life of our planet is enormous. Plants, accumulating solar energy, convert it 5
6 into the energy of chemical bonds of organic compounds, forming organic substances from inorganic ones. This process of photosynthesis releases oxygen into the atmosphere. That is, it is green plants that create food for all living organisms on the planet, are the first link in food chains, and producers in biocenoses. The Earth's atmosphere, which contains 21% oxygen and is suitable for breathing by living beings, is largely created by plants. The plant as a whole organism. All living organisms are built from cells. Unicellular (bacteria, protozoa, many algae and fungi) consist of a single cell, multicellular (most plants and animals) usually consist of many thousands of cells. Plant cells are grouped into various tissues (educational, integumentary, conductive, mechanical, basal, excretory). The structural features of the cells of these tissues allow them to perform specific functions: plant growth in height and thickness; protecting the plant from water evaporation and mechanical stress; conducting water, minerals and organic substances through the plant; provide the mechanical strength of the plant, the synthesis of organic substances, the storage of substances, and the release of substances. Tissues are located in the plant in the form of differently arranged complexes and make up the plant organs: root, stem, leaf, flower. Each organ performs its own function: the root absorbs water from the ground with minerals dissolved in it and carries it into the stem. The stem brings the leaves closer to the light and, thanks to the branching system, positions them most effectively to absorb solar energy. In addition, the stem carries various substances up and down the plant: water with minerals dissolved in it moves up from the root; down organic substances (carbohydrates, 6
7 formed during photosynthesis in leaves). The function of a green leaf is very important and unique in nature; photosynthesis occurs; the formation of organic substances (carbohydrates) from inorganic substances (carbon dioxide in air and water) with the participation of sunlight and the green pigment chlorophyll contained in green leaves and shoots of plants. Oxygen is released into the atmosphere as a byproduct of photosynthesis. With the help of leaves, two more processes occur: transpiration (evaporation of water by leaves) and plant respiration (the process of oxidation of organic substances with the release of energy, the external manifestations of which are the absorption of air oxygen by the plant and the release of carbon dioxide). The above plant organs provide daily life(nutrition, respiration, growth) plants are called vegetative. At certain periods of a plant's life, usually in spring or summer, the plant forms generative or reproductive organs, flowers and fruits, intended for sexual reproduction of plants, formation and distribution of seeds. We will begin our study of the structure of plants with the plant cell. Cytology is the science of cells. Methods for studying cells. A cell is an elementary structural and functional unit of the body of plants and animals, capable of reproduction. Complex biochemical processes of synthesis and decomposition of organic substances occur in cells, as a result of which the plant body is built and energy is released for life. Any living organism interacts with its environment, absorbing some substances from it and releasing products of its vital activity into it. This process is called metabolism. In it, two opposite and parallel processes can be distinguished: assimilation (synthesis or formation 7
8 organic substances) and dissimilation (decomposition of organic substances with the release of energy). A cell has all the properties of a living system: it exchanges substances and energy, grows, reproduces and inherits its characteristics, responds to external signals (stimulants) and is capable of movement. It is the lowest level of organization, possessing all these properties, the smallest structural and functional unit of living things. It can live and separately isolated cells of multicellular organisms continue to live and reproduce in a nutrient medium. Plant metabolism has its own unique characteristics, which are determined by the structure and functioning of plant cells. The first to see the cell was the English naturalist (physicist, astronomer and botanist) Robert Hooke while studying the integumentary tissue of the elderberry cork. He improved the microscope invented by Galileo Galilei (Italian mathematician, physicist and astronomer) in 1609 and used it to examine thin sections of plants. R. Hooke outlined his observations in the essay “Micrography”, published in 1665, where he first used the term “cell”. However, this term began to be used in its modern meaning only 150 years later. Since the plug consists of dead cells that have only walls, there has been a misconception that the main vital functions of the cell are associated with the cell walls. The contents of the cells were given secondary importance as “nutritional juice” or “plant mucus.” Only in the 19th century. the contents of the cell attracted the attention of researchers. By this time, starch grains, crystals, chloroplasts and other parts of the cell were already known. Microscopic techniques were improved and new experimental material was accumulated. In 1833, the English botanist Robert Brown discovered the nucleus, in 1839 the Czech physiologist and anatomist Jan Purkinje 8
9 cytoplasm. They also gave the name to these cell components. The accumulated data on the cellular structure of plants and animals allowed the Germans botanist Matthias Schleiden and zoologist Theodor Schwann in formulate a cellular theory, the essence of which is that the cell is the basic elementary structural unit of all living organisms. The creation of the cell theory is a significant success in biology, since it implies the unity of all living systems and unites various areas of biology that study a variety of organisms. In 1858, the German naturalist Rudolf Virchow made a general conclusion that cells can only appear from other cells: “Where a cell exists, there must be a previous cell, just as an animal comes only from an animal, and a plant only from a plant Above all living forms, be they animal or plant organisms, or their constituent parts, are governed by the eternal law of continuous development.” Virchow's concept takes on even greater significance from the point of view of evolution. There is a continuous connection between modern cells and the organisms that contain them and the primitive cells that first appeared on Earth at least 3.5 billion years ago. The science of cytology studies the structure of cells and their vital functions. The methods used to study cells are very diverse. Most cells can only be seen with a microscope, so the main method is microscopic. When describing cell sizes, micrometers and nanometers are used (1 µm = 0.001 mm; 1 nm = 0.001 µm). A major role is played by the light (photon) microscope, modern models of which provide magnification of up to 2 thousand times. 9
10 However, the capabilities of a light microscope are limited; particles smaller than 0.2 μm cannot be examined using it. An electron microscope gives a magnification of a thousand times. Here, instead of a beam of light, a stream of electrons moving at high speed is used. Modern electron microscopes have a resolving power of about 0.5 nm, about times greater than the human eye (the diameter of a hydrogen atom is about 0.1 nm). There are transmission (transmission) and scanning electron microscopes. In a transmission (transmission) microscope, a beam of electrons passes through a slice, is spread apart by electromagnetic lenses and projected onto a screen that glows from electron impacts, or onto a photographic plate. Using an electron microscope, particles with a size of 1.5 nm can be examined. The sections under study must have a thickness of no more than 0.05 microns and be specially stained. In a scanning (rastering) electron microscope, the electrons that are recorded and converted into an image come from the surface of the sample. An electron beam is focused into a thin probe and scans the sample. As a result, the sample emits secondary electrons of low energy. Different areas of the surface emit different amounts of secondary electrons. A smaller number emit depressions and grooves, and therefore appear dark, a larger number peaks and protrusions, which appear light. The result is a three-dimensional image. Electrons reflected by the surface and secondary electrons are collected, amplified and transmitted to the screen. The tissue culture method is used to study the structure and activity of living cells outside the body. The cytochemical method makes it possible to identify the presence and determine the amount of various substances in the white cell 10
11 cov, fats, carbohydrates, nucleic acids, hormones, vitamins, etc. Cell components with different densities can be separated for isolated study using the centrifugation method. The method of microscopic surgery makes it possible to extract individual components from a cell (nucleus, mitochondria, etc.). eleven
12 Lecture 2 COMPONENTS OF THE CELL. CELL WALL Examining an adult plant cell using a light microscope, you can see the following components: a dense wall, a nucleus with nucleoli located in the cytoplasm, one large or 2 3 small vacuoles occupying central part cells, plastids (green, orange, colorless), starch and protein grains, lipid droplets. Differences between a plant cell and an animal cell: the presence of plastids (chloroplasts, leucoplasts, chromoplasts); storage polysaccharide starch; the presence of a cellulose cell wall; large vacuoles. The nucleus and cytoplasm are the living parts of the cell and together constitute the protoplast. The wall and vacuoles are non-living parts of the cell, derivatives of the protoplast, products of its vital activity. Functions in the cell are distributed among various organelles. Organelles are divided into two groups: those visible under a light microscope and those visible only under an electron microscope; respectively, they speak of the microstructure and ultrastructure of the cell. Under a light microscope, nuclei with nucleoli and plastids are clearly visible; waste products of the cell: cell wall, starch grains, protein granules, calcium oxalate crystals. Under an electron microscope, you can examine the structure of the plasmalemma, tonoplast, nuclear membrane, Golgi apparatus, 12
13 ribosomes. In each group, there are organelles covered with two membranes (plastids, mitochondria, nuclear membrane); one membrane (plasmalemma, tonoplast, endoplasmic reticulum, Golgi apparatus, oleosomes, lysosomes) and membraneless (hyaloplasm, nucleoplasm, ribosomes). All components of a protoplast are usually colorless, except plastids, which can be green or orange. The substances from which a cell is built are extremely diverse. Most of all the cell contains water (60-90%), necessary for the normal course of metabolic reactions. The remainder of the chemical compounds are mainly organic substances, but there are also inorganic ones (2-6% of dry matter). The organic substances of the cell include proteins, lipids, carbohydrates, nucleic acids, from which organelles are built; enzymes (biological catalysts), hormones (growth regulators), reserve substances (temporarily excluded from metabolism), excretory substances (end products of metabolism). The cytoplasm has a membrane organization. Its structure is formed by thin (4–10 nm), rather dense films of biological membranes. They are based on lipids. Lipid molecules are arranged in an orderly manner perpendicular to the surface, in two layers. Parts of the lipid molecule that interact intensively with water (hydrophilic) are directed outward, and parts that are inert with respect to water (hydrophobic) are directed inward. Protein molecules are located on the surface of the lipid framework on both sides (surface proteins). Some proteins are immersed in the lipid layer, and some pass through it, forming areas permeable to water (transmembrane proteins). The structure of cell membranes, both plant and animal, is universal: cell membranes have a mosaic structure. Membranes form boundary layer cytoplasm, as well as the outer border of its organelles and participate in the creation of 13
14 research on their internal structure. They divide the cytoplasm into isolated compartments, in which biochemical processes can occur simultaneously and independently of each other, often in opposite directions (for example, synthesis and decay). The main property of biological membranes is selective permeability (semi-permeability): some substances pass through them with difficulty, others easily and even towards higher concentrations. Membranes largely determine the chemical composition of the cytoplasm and cell sap. The plasmalemma is a membrane that separates the cytoplasm from the cell wall and is usually tightly adjacent to it. Regulates metabolism with the environment, and also participates in the synthesis of substances. The tonoplast separates the cytoplasm from the vacuole. Its function is the same as the plasmalemma. Hyaloplasm is a liquid continuous medium in which organelles are immersed. Hyaloplasm contains enzymes and nucleic acids. It is believed that the proteins that make up the hyaloplasm form a network of thin fibrils (2-3 nm in diameter), a trabecular system that connects the organelles. This system is very dynamic; it can disintegrate when external conditions change. Hyaloplasm is capable of active movement, which can be rotational along the cell wall, if there is one large vacuole in the center, and streaming along cords crossing the central vacuole. The speed of movement depends on temperature, light intensity, oxygen supply and other factors. When moving, the hyaloplasm carries organelles with it. Hyaloplasm interconnects organelles, participates in metabolism, transport of substances, transmission of irritation, etc. Endoplasmic reticulum (endoplasmic reticulum) is a system of interconnected submicroscopic channels and cisterns penetrating the hyaloplasm, from - 14
15 bordered by membranes. There are two forms of endoplasmic reticulum: granular (rough) and agranular (smooth). The granular endoplasmic reticulum carries small ribosome organelles on its surface. She performs important functions: synthesis of enzymes, transport of substances, communication with adjacent cells through plasmodesmata (the thinnest threads of cytoplasm passing through pores in the cell walls and connecting two neighboring cells); formation of new membranes, vacuoles and some organelles. The agranular endoplasmic reticulum consists of branching tubes extending from the cisterns of the granular endoplasmic reticulum and does not have ribosomes. Usually it is less developed than granular. Participates in the synthesis and transport of essential oils, resins, and rubber. Ribosomes are organelles with a diameter of about 20 nm, located in the hyaloplasm or attached to the surface of the membranes of the endoplasmic reticulum. Each cell possesses tens of thousands or millions of these tiny, round ribonucleoprotein particles. They are also found in mitochondria and plastids. Ribosomes are composed of protein and ribonucleic acid (RNA) and do not have a membrane structure. The ribosome consists of two unequal subunits. The function of ribosomes is protein synthesis. This process occurs in ribosomes, located in a group and interconnected by a thread-like RNA or mRNA molecule (messenger or messenger RNA transfers the genetic information stored in the nucleus, necessary for the synthesis of various proteins, to the ribosomes). Such groups are called polysomes. It is believed that ribosomes are formed in the nucleus. Constant synthesis of proteins is necessary for the cell, since in the process of life the proteins of the cytoplasm and nucleus are constantly being renewed. The Golgi apparatus consists of a dictyosome and Golgi vesicles. A dictyosome is a stack of 15
16 5 7 flat tanks bounded by an agranular membrane. The diameter of the tanks is 0.2 0.5 microns, thickness nm. The tanks do not touch each other. Golgi vesicles detach from the edges of the cisterns and spread throughout the hyaloplasm. In the dictyosome, the synthesis, accumulation and release of polysaccharides (carbohydrates with a large molecular weight, consisting of residues of glucose monosaccharide molecules, etc. (C 6 H 10 O 5) n) occur. Golgi vesicles transport them, including to the plasmalemma. The membrane of the vesicles is embedded in the plasmalemma, and the contents appear outside the plasmalemma and can be included in the cell wall. Golgi vesicles can be incorporated into the tonoplast. It is believed that the endoplasmic reticulum takes part in the formation of dictyosomes (Camillo Golgi, Italian histologist, physician and pathologist). Oleosomes are round shiny bodies with a diameter of 0.5-1 microns. These are centers for the synthesis and accumulation of vegetable oils. They are detached from the ends of the strands of the endoplasmic reticulum. The membrane located on the surface of the oleosome is reduced as oil accumulates, and only the outer layer remains. Lysosomes are vesicles measuring 0.5-2 microns with a membrane on the surface. Contain enzymes that can break down proteins, lipids, polysaccharides and other organic compounds. They are formed in the same way as spherosomes, from strands of the endoplasmic reticulum. Their function is the destruction of individual organelles or areas of the cytoplasm (local autolysis), necessary for cell renewal. Mitochondria are organelles with a length of 2-5 microns, a diameter of 0.3-1 microns, oval, round, cylindrical and other shapes, delimited from the cytoplasm by two membranes. The inner membrane forms projections into the mitochondrial cavity in the form of ridges or tubes, called cristae.
17 mi. Cristae significantly increase the membrane surface of the mitochondria. The space between the cristae is filled with a liquid matrix substance, which contains ribosomes and contains deoxyribonucleic acid (DNA). The surface of the inner membrane is covered with tiny bodies with a spherical head and stalk (ATP-somes). (Adenosine triphosphoric acid consists of residues of a nitrogenous base, ribose carbohydrate and phosphoric acid; carries out energy transfer). In mitochondria, the processes of breakdown of carbohydrates, fats and other organic substances with the participation of oxygen (respiration) and ATP synthesis occur. The energy released during respiration is converted into the energy of macroergic (energy-rich) bonds of the ATP molecule, which is then used to carry out the vital processes of cell division, absorption and release of substances, synthesis, etc. It is believed that mitochondria can be formed in two ways: division and from initial particles separated from the nucleus. Respiration is the breakdown of organic substances with the participation of atmospheric oxygen, as a result of which energy is released and carbon dioxide and water are formed. Energy is accumulated in high-energy bonds of adenosine triphosphoric acid (ATP) molecules and is used for various types of work in the cell. Mitochondria are capable of movement. They are concentrated around the nucleus, chloroplasts and other organelles, where life processes occur most energetically. It is an obligatory organelle of both plant and animal cell. Plastids. Chloroplasts. Double-membrane organelles 4-6 µm long, 1-3 µm thick. A cell can contain from 1 to 50 chloroplasts. The stroma is penetrated by a system of parallel membranes. The membranes look like flat bags of thylakoids or lamellae. The pain is 17
18 In most higher plants, some of the thylakoids have a discoid shape. These thylakoids are collected in stacks called grana. The grana are interconnected by stromal thylakoids. The inner membrane of the chloroplast membrane sometimes forms folds and passes into the thylakoid stroma. The thylakoid membranes contain molecules of chlorophyll, carotenoids and other molecules involved in the process of photosynthesis. The stroma contains DNA molecules, ribosomes, lipid droplets called plastoglobules, primary starch grains and other inclusions. Photosynthesis is the formation of organic substances (carbohydrates) from inorganic substances (carbon dioxide from air and water) in the cells of green plants using solar energy. Oxygen is released into the atmosphere as a by-product. Leukoplasts. Colorless plastids. The internal membrane system is less developed than that of chloroplasts. The stroma contains DNA molecules, ribosomes, and plastoglobules. Function: synthesis and accumulation of reserve nutrients (starch, proteins). Leukoplasts that accumulate starch are called amyloplasts. They accumulate secondary starch. Reserve protein can be deposited in the form of crystals or amorphous granules, oil in the form of plastoglobules. Chromoplasts. The internal membrane system is often absent. Contains carotenoids. Chromoplasts are found in ripe fruits and flowers. The function helps to attract pollinating insects to plants and the distribution of fruits and seeds by animals. The nucleus is the place of storage and reproduction of hereditary information that determines the characteristics of a given cell and the entire organism as a whole, as well as the control center for protein synthesis. The diameter of the cell nucleus of the vegetative organs of angiosperms is microns. 18
19 Nuclear envelope. Thickness nm (2 membranes with perinuclear space between them). The inner membrane is agranular, and ribosomes are attached to the outer membrane and it forms projections that pass into the endoplasmic reticulum of the cytoplasm. The nuclear envelope has nuclear pores complex structure; through them macromolecules pass from the nucleoplasm to the hyaloplasm and in the opposite direction. The nuclear envelope controls the exchange of substances between the nucleus and the cytoplasm and is capable of synthesizing proteins and lipids. Nucleoplasm is a colloidal solution in which chromosomes and nucleoli are located. The nucleoplasm contains various enzymes and nucleic acids. It not only communicates between the organelles of the nucleus, but also transforms substances passing through it. Chromosomes can be in two states. In working condition, these are thin (10 nm) filamentous structures decondensed to varying degrees, actively participating in metabolism. They are visible only under an electron microscope. During nuclear division, the chromosomes condense as much as possible, becoming short and thick (visible under a light microscope). They perform the function of distributing and transferring genetic information, do not participate in the metabolic process, absorb many dyes and are intensely colored. By chemical nature, a chromosome is a nucleoprotein consisting of DNA (deoxyribonucleic acid) and protein. One of the most important properties of DNA is replication (self-duplication), in which chains of nucleotides diverge and each of them completes the lost one. The section of the DNA molecule that determines the synthesis of one of the cell-specific proteins is called a gene. The sequence of nucleotides in a DNA molecule, unique to each organism, is called the genetic code. 19
20 The structure of DNA was established by the American biochemist J. Watson together with the English physicist Francis Crick, working in Cambridge University(England). Using X-ray diffraction data from DNA crystals, Watson and Crick created a model of DNA in the form double helix, assuming that this helix consists of two polynucleotide chains. Based on Watson Crick's model, a modern understanding of the principle of gene operation was developed and the foundations of ideas about the transfer of biological information were laid. In 1962, Watson and Crick were awarded the Nobel Prize in Physiology or Medicine for their discovery molecular structure nucleic acids and their role in the transmission of hereditary information in living matter. The nucleolus is a round body with a diameter of 1-3 microns, consisting mainly of protein and RNA. The nucleolus usually contacts a secondary constriction of the chromosome, called the nucleolar organizer, on which template rRNA synthesis takes place. Then the rRNA combines with the protein, resulting in the formation of granules of ribonucleoprotein precursors of ribosomes, which enter the nucleoplasm and penetrate through the pores of the nuclear membrane into the cytoplasm, where their formation is completed. The implementation of hereditary information contained in the genotype of an organism occurs as a result of protein synthesis. Protein synthesis occurs on ribosomes in the cytoplasm of the cell. Protein synthesis carries matrix character. Amino acids by themselves cannot combine into a polypeptide chain; this requires a template matrix. The matrix determines the possibility of creating a polypeptide chain, as well as its specificity (amino acid sequence). Nucleic acid serves as the template for protein synthesis. This entire chain of events (DNA pro-mRNA (mRNA precursor) mRNA protein) is called gene expression and includes: 20
21 transcription synthesis of pro-mRNA with a sequence of bases complementary (corresponding) to DNA; post-transcriptional changes, in which pro-mRNA is processed into mRNA and transferred to the cytoplasm on ribosomes; translation of the process of protein synthesis with a specific sequence of amino acids. The blueprint for protein construction is encrypted in DNA and is located in the nucleus. Meanwhile, protein synthesis is carried out on ribosomes, which are mainly located in the cytoplasm. The DNA molecules are too large and cannot escape through the pores of the nucleus. The transfer of information from DNA is carried out using information or messenger RNA (mRNA). This process is called transcription (rewriting). Cell division. Plant growth occurs mainly due to an increase in the number of cells in the growing organs. The main method of division of somatic cells is mitosis. During mitosis, an orderly distribution of DNA occurs between the daughter nuclei. As a result of mitosis, the mother cell is divided into two, and the number and shape of chromosomes of the daughter cells are identical to the mother cell. The process of mitosis has 4 phases: prophase, metaphase, anaphase and telophase. The period between two cell divisions is called interphase. In interphase, the cell prepares for division and the substances necessary for this are synthesized. It is divided into phases G 1, S and G 2. S is the phase of DNA synthesis, phase G (from the English gap) is the phase before (G 1) and after (G 2) DNA synthesis. In the G 1 phase, the interphase cell contains a characteristic amount of DNA for a given species; in G 2, this amount is already doubled. Interphase and mitosis closely constitute the mitotic cycle of a cell. The duration of the mitotic cycle is approximately one hour, with interphase being the longest part. 21
22 Meiosis is a method of division in which 4 cells are formed with the number of chromosomes 2 times less than that of the mother cell. Meiosis in higher plants occurs during the formation of spores. The essence of meiosis is to reduce the number of chromosomes in cells by half and transition cells from a diploid state to a haploid state. The entire fund of genetic information of everyone cell nucleus the genome is distributed among a certain constant number of chromosomes. This number (n) is specific to the species. In corn, n = 10, in humans, n = 23. Haploid cells contain one set of chromosomes n, diploid 2n, so all information is presented twice. Sex cells are haploid. In higher plants and animals, somatic cells are diploid and contain one paternal and one maternal set of chromosomes. Meiosis consists of two successive divisions not separated by interphase. During the first division, the same four phases are distinguished as in mitosis, but they have fundamental differences. In anaphase of the first division, it is not the chromatids that move to the poles, but the homologous chromosomes. The second division occurs according to the type of mitosis. The diversity of chromosome sets of cells formed as a result of meiosis determines the diversity of characteristics in subsequent generations. This is the basis for the evolution of the species. Cell wall. A characteristic feature of a plant cell is the presence of a solid cell wall. The cell wall determines the shape of the cell, gives mechanical strength and support to plant cells and tissues, and protects the cytoplasmic membrane from destruction under the influence of hydrostatic pressure developed inside the cell. The cell wall is an anti-infective barrier, preventing microorganisms from entering the cell; takes part in the takeover 22
23 mineral substances, being a kind of ion exchanger. Participates in the transport of water and substances throughout the plant. Participates in the synthesis of substances, such as cellulose. Young growing cells are characterized by a primary cell wall. As they age, a secondary structure forms. The primary cell wall has a simpler structure and less thickness than the secondary one. Cell wall components are waste products of the cell. They are released from the cytoplasm and undergo transformations on the surface of the plasmalemma. The basis of the cell wall is made up of intertwined micro- and macrofibrils of cellulose. Cellulose, or fiber (C 6 H 10 O 5) n, is a long unbranched chain consisting of 1 14 thousand D-glucose residues. Cellulose molecules are combined into a micelle, micelles are combined into a microfibril, microfibrils are combined into a macrofibril. Macrofibrils, micelles and microfibrils are connected into bundles by hydrogen bonds. The diameter of the micelle is 5 nm, the diameter of the microfibril is nm, and the diameter of the macrofibril is 0.5 μm. Primary cell walls contain, on a dry matter basis: 25% cellulose, 25% hemicellulose, 35% pectin and 1 8% structural proteins. Secondary cell walls contain up to 60–90% cellulose. Thickening of the shell occurs by applying new layers to the primary shell. Due to the fact that the imposition is already on hard shell, cellulose fibrils in each layer lie parallel, and in adjacent layers at an angle to each other. As cells continue to age, the membrane matrix can be filled with various substances, lignin and suberin. Lignin is a polymer formed by the condensation of aromatic alcohols. The inclusion of lignin is accompanied by 23
24 is given by lignification, an increase in strength and a decrease in elongation. Suberin is a polymer whose monomers are saturated and unsaturated hydroxy fatty acids. Cell walls impregnated with suberin (suberization) become difficult to permeate water and solutions. Cutin and wax may be deposited on the surface of the cell wall. Cutin consists of hydroxy fatty acids and their salts, is released through the cell wall onto the surface of the epidermal cell and is involved in the formation of the cuticle. The cuticle may contain waxes, which are also secreted by the cytoplasm. The cuticle prevents water evaporation and regulates the water-thermal regime of plant tissues. 24
25 Lecture 3 PLANT TISSUE The transition of plants from relatively monotonous living conditions in an aquatic environment to terrestrial ones was accompanied by an intensive process of dismemberment of a homogeneous vegetative body into organs: stem, leaves and roots. These organs consist of cells of various structures that form easily distinguishable groups. Groups of structurally homogeneous cells that perform the same function and have a common origin are called tissues. Often several tissues of the same origin form a complex that functions as a single unit. The science of histology studies tissues. There are six main groups of tissues: meristematic (educational), integumentary, basic, mechanical, conductive and excretory. Meristematic tissues. Plants, unlike animals, grow and form new organs throughout their lives. This is due to the presence of meristematic tissues, which are localized in certain places of the plant. The meristem consists of tightly packed living cells. The cavity of such a cell is filled with cytoplasm, a large nucleus is located in the center, there are no large vacuoles, the cell wall is very thin, primary. Meristem cells are characterized by two main properties: intensive division and differentiation, i.e., transformation into cells of other tissues. 25
26 Differentiation (differentiation) is the acquisition by cells of the same genotype individual differences in the process of ontogenesis. Based on the time of occurrence, primary and secondary meristems are distinguished. The primary meristem appears at the very beginning of the development of the organism. The fertilized egg divides and forms an embryo, which consists of a primary meristem; the secondary meristem arises, as a rule, later from the primary or from cells of already differentiated tissues. Primary tissues are formed from the primary meristem, and secondary tissues are formed from the secondary meristem. Based on their location, four groups of meristems are distinguished. Apical (apical) meristem. Located at the tops of the main and lateral axes of the stem and root. It determines mainly the growth of organs in length. It is primary in origin. At the top of the stem there is a small group of parenchyma cells (rarely one cell), which divide quite quickly. These are the initial cells. Below are derivatives of the initial cells, the division of which occurs less frequently. And even lower in the meristem, three groups of cells are separated, from which the tissues of the primary body are differentiated: protoderm, the surface layer of cells that gives rise to the integumentary tissue; procambium elongated meristem cells with pointed ends located along vertical axis groups (cords), from which conductive and mechanical tissues and a secondary meristem (cambium) are formed; the main meristem that gives rise to the main tissues. The apical meristem of the root has a slightly different structure. At the apex there are initial cells that give rise to three layers: the dermatogen, which differentiates into the epiblema; periblema, giving rise to the tissues of the peri- 26
27 cervical cortex; pleroma, differentiating in the tissue of the central cylinder. Lateral (lateral) meristem. It is located in a cylinder along the axial organs parallel to their surface. Usually it is secondary. Causes the growth of organs in thickness. More often it is called the cambium. Intercalary (intercalary) meristem. It is laid at the base of the internodes of shoots, leaves, peduncles and other organs. This is the primary or secondary meristem; it determines the lengthwise growth of organs. Wound (traumatic) meristem. Occurs on any part of the plant body where injury is caused. It is secondary in origin. Integumentary tissues. The main purpose of integumentary tissue is to protect the plant from drying out and other adverse environmental influences. Depending on the origin, three groups of integumentary tissues are distinguished: primary epidermis, secondary cork, tertiary crust. Epidermis. The primary integumentary tissue, which is formed from the protoderm, covers the leaves and young stems. Most often, the epidermis consists of a single layer of living, tightly packed cells. They contain few or (more often) no chloroplasts at all, and they are photosynthetically inactive. The cell walls are usually tortuous, which ensures a strong connection between them. The thickness of the walls is not the same: the outer ones, bordering the external environment, are thicker than the rest and are covered with a layer of cuticle. The protective function of the epidermis is enhanced by the outgrowths of its cells (trichomes), hairs of various structures, scales, etc. The epidermis has special formations for gas exchange and transpiration - stomatal apparatus, consisting of two guard cells and an intercellular space between them, 27
28 called the stomatal fissure. Guard cells contain chloroplasts. Their wall on the side of the epidermal cells is much thinner than on the side of the gap. The epidermal cells adjacent to the guard cells often have a different shape than the rest. Such cells are called secondary or parastomatal. The stomatal apparatus of terrestrial plants is located mainly on the lower side of the leaf blade, and in the floating leaves of aquatic plants only on the upper side. Cork. Due to the growth of the stem in thickness, the epidermal cells become deformed and die. By this time, the secondary integumentary tissue cork appears. Its formation is associated with the activity of the secondary meristem of the cork cambium (phellogen), arising from subepidermal or deeper cells, and sometimes from epidermal cells. The cells of the cork cambium divide tangentially (by partitions parallel to the surface of the stem) and differentiate in the centrifugal direction into a cork (phellema), and in the centripetal direction into a layer of living parenchyma cells (phelloderm). A complex consisting of three tissues: phellogen, phellem and phelloderm is called periderm. Only the cork performs a protective function. It consists of regular radial rows of tightly closed cells, on the walls of which suberin is deposited. As a result of suberization of the walls, the contents of the cells die. For transpiration and gas exchange, the plug contains special lentil formations filled with rounded cells, between which there are large intercellular spaces. A crust (rhythid) is formed in trees and shrubs to replace a cork, which breaks after 2-3 years under the pressure of the growing stem. In the deeper tissues of the cortex, new areas of cork cambium are laid down, giving rise to new layers of cork. Therefore, the outer tissues become isolated from the central part of the stem, become deformed and die. On the surface 28
29 of the stem, a complex of dead tissue is formed, consisting of several layers of cork and dead sections of bark. The outer layers of the crust are gradually destroyed. Basic fabrics. This name combines the tissues that make up the bulk of the various organs of the plant. They are also called the performing parenchyma, the main parenchyma, or simply the parenchyma. The ground tissue consists of living parenchyma cells with thin walls. There are intercellular spaces between the cells. Parenchyma cells perform a variety of functions: photosynthesis, storage of reserve products, absorption of substances, etc. The following main tissues are distinguished. Assimilation, or chlorophyll-bearing, parenchyma (chlorenchyma) is located in the leaves and bark of young stems. The cells of the assimilative parenchyma contain chloroplasts and carry out photosynthesis. Storage parenchyma is located mainly in the core of the stem and root bark, as well as in the reproductive organs of seeds, fruits, bulbs, tubers, etc. Storage tissue can also include water-storing tissue of plants in arid habitats (cacti, aloe, etc.). The absorptive parenchyma is most typically represented in the absorptive zone of the root (root hair zone). Aerenchyma is especially well expressed in the underwater organs of plants, in aerial and respiratory roots. It has large intercellular spaces interconnected into one ventilation network. Mechanical fabrics. Mechanical tissues together form a framework that supports all plant organs, resisting their fracture or rupture. These tissues consist of thick-walled cells that are often (but not always) lignified. In many cases these are dead cells. 29
30 In axial organs these are mainly prosenchymal cells, in leaves and fruits they are parenchymal. Depending on the shape of the cells, the chemical composition of the cell walls and the method of their thickening, mechanical tissues are divided into three groups: collenchyma, sclerenchyma, sclereids. Collenchyma consists of living, usually parenchyma cells with unevenly thickened cellulose walls. If the thickenings are located in the corners, then such collenchyma is called angular. If two opposite walls thicken, while the other two remain thin, collenchyma is called lamellar. The walls of collenchyma cells are capable of stretching, as they have thin sections, so it serves as a support for young growing organs. Collenchyma is more common in dicotyledonous plants. Sclerenchyma consists of prosenchymal cells with uniformly thickened walls. Only young cells are alive. As they age, their contents die off. This is a widespread mechanical tissue of the vegetative organs of land plants. By chemical composition cell walls, two types of sclerenchyma are distinguished: bast fibers, the wall is cellulose or slightly lignified, wood fibers (libriform), the wall is always lignified. Sclereids. These are dead parenchyma cells with uniformly thick lignified walls. They are common in fruits (stonous cells), leaves (supporting cells) and other organs. Conductive tissues are specialized tissues that carry out long-distance transport of substances between plant organs. If substances in the plant body move from cell to cell in the tissues of one organ, then this is short-range transport, it goes through unspecialized tissues. Long-distance transport of substances in a plant occurs in two directions: from roots to leaves (ascending current) 30
31 and from leaves to roots (downward current). Organic substances are synthesized in the leaves. This is air feeding. Roots absorb water from the soil with minerals dissolved in it. This is soil nutrition. In accordance with this, there are two main routes of transport of nutrients: the path along which water and mineral salts rise from the root along the stem to the leaves, and the path through which organic substances from the leaves are sent to all other plant organs, where they are consumed or deposited in stock Vessels (tracheas) and tracheids are conductive tissues through which water and mineral salts move. Vessels (tracheas) are tubes consisting of segments. They differentiate from a vertical row of procambium or cambium cells, in which the lateral walls thicken and become lignified, the contents die, and one or more perforations are formed in the transverse walls. The average length of the vessels is 10 cm. Depending on the shape of the wall thickenings, the vessels are ringed, spiral, mesh, etc. Ringed and spiral vessels have a small diameter. They are characteristic of young organs, since their walls have non-lignified areas and are capable of stretching. Mesh and porous vessels are much larger in diameter, their walls are completely lignified. They usually form later than the ringed and spiral vessels of the cambium. Tracheids are long prosenchymal cells whose walls have bordered pores. Tracheids begin to perform their conducting function when their contents die. The length of tracheids is on average 1 10 mm. Vessels and tracheids also perform a mechanical function, giving strength to the plant. They function for several years until they become clogged with surrounding living parenchyma cells. Outgrowths of 31
The last 32, penetrating through the pores into the cavity of the vessel, are called tills. Sieve tubes are conductive tissue through which the movement of organic substances synthesized in the leaves occurs. This is a vertical row of living cells (segments), whose transverse walls are pierced by perforations (sieve plates). The wall of the sieve tube segment is cellulose, the nucleus is destroyed, and most of the cytoplasmic organelles are degraded. In the protoplast, fibrillar structures of a protein nature arise (phloem protein). Near the sieve tube segment there are usually one or more so-called accompanying cells (companion cells) that have a nucleus. The presence of a large number of mitochondria in the accompanying cells gives reason to believe that they provide energy for the process of movement of organic substances through sieve tubes. The sieve tube segment and the accompanying cell adjacent to it are formed from one meristem cell due to its division by a vertical septum. Sieve tubes usually function for one year. In autumn, the sieve plates become impermeable to plastic substances due to the clogging of the perforations by a polysaccharide close to cellulose, callose. By the structure of conducting tissues one can judge the evolutionary level of the plant. Tracheids are more primitive formations than vessels. Among the vessels, the more primitive ones will be those whose ends of the segments are beveled and have several perforations. One large perforation is a progressive sign. Sieve tubes with obliquely set plates and many sieve fields are considered primitive, and those with horizontal sieve plates and a small number of sieve fields are considered progressive. 32
33 Vessels, tracheids and sieve tubes are located in plants, as a rule, not randomly, but are collected in special xylem and phloem complexes. Xylem (wood) consists of vessels and tracheids, wood parenchyma and (not always) wood fibers (libriform). Water and minerals move through the xylem. Secondary xylem is called wood. Phloem consists of sieve tubes and accompanying cells, bast parenchyma and (also not always) bast fibers. Organic substances move through the phloem. The secondary phloem is called phloem. Xylem and phloem, in turn, are often (but not always) located inside plant organs in the form of vascular-fibrous, or vascular, bundles. If there is a cambium between the phloem and xylem, then such bundles are called open. Thanks to the activity of the cambium, new elements of xylem and phloem are formed, so the bundle grows over time. Open bunches are characteristic of dicotyledons. In closed bundles there is no cambium between the phloem and xylem, so no growth occurs. Monocots and, as an exception, some dicotyledons, in which the cambium ceases to function very early (for example, in species of the genus Buttercup) have closed bundles. Vascular bundles are also classified according to the relative position of phloem and xylem. Collateral phloem and xylem are located side by side, with the phloem facing the periphery of the axial organ and the xylem towards the center. Bicollateral phloem is adjacent to the xylem on both sides, the outer portion of the phloem is larger than the inner one; characteristic of pumpkin, nightshade, bindweed. Concentric is of two types: xylem surrounds the phloem; amphivasal (mainly in monocots); phloem surrounds the amphicribral xylem (in ferns). 33
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4. ANATOMY OF VEGETATIVE ORGANS 4.1. Laboratory work 8. “Primary and secondary structure of the stem. Modifications of the stem" Purpose of the work: to become familiar with the primary and secondary structure of the stem of angiosperms
1. Nitrifying bacteria are classified as 1) chemotrophs 2) phototrophs 3) saprotrophs 4) heterotrophs TOPIC “Photosynthesis” 2. The energy of sunlight is converted into chemical energy in the cells of 1) phototrophs
Botany is a set of botanical disciplines whose object of study is the plant.
Botany is divided into a number of botanical disciplines.
Cytology - the structure of a plant cell.
Anatomy - deals with the study of the internal structure of a plant.
Morphology – deals with the study of the external structure of a plant.
Plant physiology (respiration, nutrition, water nutrition.)
Phylogeny - the origin of plants, how they adapted..
Plant geography is the study of the location of plants on the earth's surface.
Phytocenology – interaction of plants.
Paleobotany is the study of plants that existed in different eras.
Knowledge of botanical knowledge for humans:
Photosynthesis:
CO2+ H2O =>C6H12O6+ O2
C6H12O6 is oxidized in mitochondria.
C6H12O6 + O2 => CO2+ H2O + Qrespiration (biological oxidation).
Anatomy and morphology of plants Topic: Plant cell and its products.
In the body of a plant organism there are groups of cells that perform a certain common function, have the same structure, a single origin and occupy a certain place. This is plant tissue.
There are many classifications of fabrics. For example: dead and living, parenchymal and prosenchymal (ratio of cell length and width)
Parenchymal (length greater than or equal to the width of the cell)
Prosenchymal (length is 3 or more times greater than width)
Fabrics can be divided into:
Educational
Permanent
Cells educational fabric are divided into:
a) integumentary
b) mechanical
c) conductive
d) excretory
e) main parenchymal
This classification is called morphological-physiological.
The tissues arose when the plants left the aquatic environment.
Educational fabrics.
Meristems– i.e. dividing tissues.
1) Forms new cells and ensures plant growth (in height and width).
2) a meristematic cell is characterized by long-term youth, and therefore these cells are small in size, colorless, and easily damaged.
3) The cytoplasm is dense, occupying a large volume of the cell, the nucleus is large, usually lies in the middle of the cell.
There are many mitochondria, small colorless plastids - leucoplasts. There is a Golgi apparatus. There are few waste products, because meristematic cells begin to divide very quickly, therefore there are no reserve nutrients in the cell, vacuoles with cell sap are small in small quantities. The cell membrane is very thin, easily extensible, primary.
To ensure growth processes, cells of the educational tissue of higher plants divide only by mitosis (meiosis can occur in living beings at various stages of development (ontogenesis): during the formation of gametes (animals), during the first division of the zygote (fungi, algae), during the formation of spores (higher plants))
Topic: Types of meristems.
Educational tissues can be located in different parts of the plant body.
There are 3 types of meristems:
located at the tips of the stem or root - apical (apical)
located inside the organ, among other tissues - lateral (lateral)
intercalary (insert)
Apical and intercalary meristems provide preferential growth in height, while lateral meristems provide an increase in thickness.