Drawing who wants to be who. Lesson in the preparatory group for drawing "Who do I want to be?". Didactic game "Whose things are these?"
The leaf is an obligatory vegetative organ of the vast majority of plant organisms. For the first time we get acquainted with its structure by studying the higher spore plants - mosses, which have leaf-stem forms.
These include, for example, sphagnum and cuckoo flax. Being the lateral parts of the shoot, the leaves usually consist of a leaf blade and petiole, which are attached to the stem. They perform the most important functions: they serve as the main organs that carry out photosynthesis, transpiration (evaporation of water) and respiration. If, for some reason, these vegetative organs are forced to take on other functions, then the plant undergoes a modification of the leaves. In our article, we will find out what conditions lead to the emergence of an atypical structure and special properties of leaf blades in higher spore, gymnosperms and flowering plants.
Influence of abiotic factors on the morphological characteristics of the organism
Habitat conditions are powerful shaping forces that can radically change the external structure of both plants and animals. The adaptations that arise in them are adaptive in nature and were well studied by Ch. Darwin. The scientist considered their appearance the result of the action of the struggle for existence - one of the driving factors of natural selection. It is from this position that modern biology explains the modification of leaves observed in some biological species. Everyone knows examples illustrating the structural features of xerophyte organisms. Forced to live in an environment where water is the limiting factor, plants of the southern steppes, semi-deserts and deserts have a low transpiration coefficient.
It is explained by a decrease in the evaporating area of leaf blades. In the end, the modification of the leaves reaches such a level in xerophytes that they turn into thorns, for example, in saxaul or cacti. The transition of leaves into scales that have lost the ability to photosynthesize in horsetails has the same reason.
How do leaves perform a supporting and protective function
From the course of botany it is known that mechanical properties plant parts such as root and stem. The tissues of the leaf blade do not have a sufficiently developed system of reinforcing elements, with the exception of the vascular-fibrous bundles located in the veins. However, for some plant species with a climbing stem shape and a weak, superficial type of root system, a special leaf structure is inherent. The modification of leaves, for example, in peas, is expressed in the appearance of tendrils that perform a supporting function and fix the stem in space. The property of protection from adverse conditions is characteristic of dry leaves - scales of bulbs or buds of flowering plants, covering the delicate rudimentary leaves.
carnivorous plants
Exotic representatives of the flora: nepenthes and sundew - feed heterotrophically, like animals. The modification of their leaves is associated with new functions: to catch and further digest small insects stuck to the walls of leaf blades. They are covered with sticky trap hairs that firmly hold the victim. Interestingly, predator plants usually live on soils with a low nitrogen content, the lack of which they more than make up for at the expense of obtained animal proteins.
Examples of modification of the leaves of gymnosperms and flowering plants
Everyone knows the fact that representatives of the Coniferous class are easily recognizable by the needle structure of their leaves, called needles. It has a small surface and deep-seated stomata, covered with a layer of wax in winter. All this helps pine, larch, cedar to minimize water loss during the cold period. Flowering plants, such as aloe and juvenile, conserve moisture in a different way. Their leaves, on the contrary, become fleshy and succulent reservoirs in which water is stored all year round.
Some types of angiosperms (cacti, acacia, barberry) use their leaves-thorns as weapons. It protects the plant from mechanical damage or being eaten by animals. Many examples can be cited illustrating the modification of leaves in various biological species that form the modern flora of the Earth. All of them are various kinds of adaptations aimed at the survival of plants in various environmental conditions.
1) Botany is the science of plants.It studies the life of plants, their structure, vital activity, living conditions, origin and evolutionary development. This is part of the tasks of botany, but, in addition, the task is to study the plant world both separately and on a large scale.
The role of plants in nature:
1. Participate in the formation of organic substances, accumulate a large amount of chemical energy in the products of photosynthesis.
2. Maintain the level of oxygen in the atmosphere. Prevent the accumulation of excess carbon dioxide in the atmosphere.
3. They play a leading role in the circulation of mineral and organic substances, which ensures the continuous existence of life on Earth.
4. Reduce the greenhouse effect, reduce the temperature to the current level.
5.Vegetation takes an active part in the formation of soils.
6. Prevent soil erosion, fix ravines and mountain slopes.
The role of plants in human life:
1.Used for food.
2. Medicinal plants.
3.Technical plants used in industry as raw materials.
4. Plants as a source of vitamins.
5. Aesthetic value - they decorate our lives, bring joy.
2) Androecium- a collection of stamens in a flower. The stamen consists of a filament and an anther. The anther has 2 thecae, each thecae has 2 microsporangia or a pollen nest.
There are 2 processes in the anther:
- microsporogenesis- the process of formation of male microspores in microsporangia
- 2) Microgametogenesis- development from microspores of a male gametophyte or pollen grain. The microspore divides by mitosis, resulting in the formation of two cells. They represent the male gametophyte or pollen grain.
One of the cells of the pollen grain is called vegetative and is capable of forming a long process, or pollen tube, reaching the embryo sac. The second (generative) cell, floating in the cytoplasm of a vegetative cell, when dividing, gives two male gametes - flagellated spermatozoa or flagellated spermatozoa. The spermatozoa reach the egg through the archegonial canal. Sperm, moving along the pollen tube, reach the embryo sac and participate in fertilization.
3) root metamorphosis.
Metamorphosis is a deep transformation of the structure of the body that occurs in the course of individual development.
1) Storage roots. They are usually thickened. Strongly thickened adventitious roots are called root cones, or root tubers. Many, more often biennial, plants with a tap root system develop a formation called root crop. Both the main root and the lower part of the stem take part in the formation of the root crop.
2) Many bulbous and rhizomatous plants form retractors roots. They can shorten and pull the shoot into the soil to the optimum depth during a summer drought or winter frosts. Retracting roots have thickened bases with transverse wrinkling.
4) Respiratory roots, or pneumatophores are formed in some tropical woody plants living in conditions of lack of oxygen. Pneumatophores grow vertically upwards and protrude above the soil surface. Through a system of holes in these roots, connected with the aerenchyma, air enters the underwater organs.
5) In some plants, to maintain shoots in the air, additional support roots. They depart from the horizontal branches of the crown and, having reached the soil surface, branch intensively, turning into columnar formations that support the crown of the tree ( columnar banyan roots) . stilted roots extend from the lower parts of the stem, giving the stem stability. They are formed in mangrove plants, plant communities that develop on tropical oceans flooded at high tide, and also in corn. Ficus rubbery are formed plank-shaped roots. Unlike columnar and stilted, they are by origin not adventitious, but lateral roots.
The roots of many plants form a symbiosis with hyphae of soil fungi, called mycorrhiza. Mycorrhiza is formed on sucking roots in the absorption zone.
There are two main types of mycorrhiza: 1) external (surrounds the outside. In many edible mushrooms) 2) internal (The mushroom component makes it easier for the roots to obtain water and mineral elements from the soil, often fungal hyphae replace root hairs. In turn, the fungus receives carbohydrates and other nutrients from the plant. )
On the roots of legumes, special formations appear - nodules in which bacteria from the genus Rhizobium settle. These microorganisms are able to assimilate atmospheric molecular nitrogen, converting it into a bound state. Part of the substances synthesized in the nodules are absorbed by plants, bacteria, in turn, use the substances found in the roots. This symbiosis is of great importance for Agriculture. Legumes are rich in protein due to the additional source of nitrogen. They provide valuable food and fodder products and enrich the soil with nitrogenous substances.
Escape metamorphoses.
Underground:
1) rhizome - a long-lived underground shoot that performs the functions of deposition of reserve nutrients, renewal, and sometimes vegetative propagation.
2) stolons - short-lived thin underground shoots bearing underdeveloped scaly leaves. Stolons serve for vegetative reproduction, settlement and territory capture. Spare nutrients are not deposited in them.
3) the tuber has a spherical or oval shape, the stem is strongly thickened, reserve nutrients are deposited in it, the leaves are reduced, and buds form in their axils. The stolons die off and are destroyed, the tubers overwinter, and on next year give rise to new above-ground shoots.
4) bulb - an underground shoot with a very short flattened stem and scaly fleshy succulent leaves that store water and soluble nutrients, mainly sugars.
5) The corm looks like an onion, but its scaly leaves are not storage; they are dry, and reserve substances are deposited in the thickened stem part (saffron, gladiolus).
b) Caudex is a perennial organ of shoot origin of perennial herbs and shrubs with a well-developed taproot that persists throughout the life of the plant. Together with the root, it serves as a place of deposition of reserve substances and carries many renewal buds, some of which may be dormant (dandelion, wormwood)
Overground:
1) stolons - short-lived shoots, the function of which is vegetative reproduction, resettlement and territory capture.
2) Water storage organs can be leaves or stems, sometimes even buds. Such succulent plants are called succulents (aloe, agave, crassula, rhodiola, or golden root).
3) Head of cabbage - a succulent organ that forms in ordinary cultivated cabbage. The adaptive form of the head of cabbage arose as a modification of a part of the rosette.
4) The spines of cacti are of leaf origin. Leaf spines are often found in non-succulent plants (barberry). In many plants, spines are not of leaf, but of stem origin (wild apple, wild pear).
5) Tuber - a thick near-earth part of the stem in representatives of the orchid family. Serves plants as a special organ for storing water and nutrients.
b) Cladodium - a modified lateral shoot with the ability to grow long, with green flat long stems that act as a leaf. As an organ of photosynthesis, the cladodium has a well-developed chlorophyll-bearing tissue.
7) Phyllocladium - a modified leaf-like flattened lateral shoot with limited growth and performing the functions of a leaf. Phyllocladia develop from lateral buds, so they are always found in the axil of a small membranous or scaly leaf. Performing the function of photosynthesis.
8) Antennae - a flagellate branched or unbranched shoot of a metameric structure, typically devoid of leaves. Stem tendrils, as a highly specialized shoot, perform a supporting function (cucumber, watermelon)
Leaf metamorphosis:
1. spines- one of the most common modifications; they serve as a defense against being eaten by animals. In this case, the leaf either completely turns into a thorn (cacti, euphorbia, barberry, white locust, camel thorn), or part of it turns into a thorn (thistle, thistle, holly).
2. tendrils(in compound leaves of some plant species) cling to a support, carrying the entire shoot to the light. At the same time, either the upper leaves of a complex leaf (pea, vetch), or the entire leaf can turn into a tendril, and the stipules (some types of ranks) perform the function of photosynthesis.
3. The storage function is performed juicy scales bulbs (onion, garlic), aloe leaves, head of cabbage.
4. Covering scales buds protect delicate rudimentary leaves and growth cone from adverse environmental conditions.
5. trapping devices provide the life of insectivorous plants in swamps in conditions of a lack of nitrogen and other elements of mineral nutrition. The leaves of such plants have changed beyond recognition, turning into traps (Venus flytrap), jugs (nepentes). The leaves of some plants with their shiny, brightly colored droplets on the hairs attract ants, flies, mosquitoes, and other small insects; the juice released at the same time contains digestive enzymes (dew).
Typically, a sheet performs three functions:
- photosynthesis (organic nutrition);
- transpiration (evaporation of water);
- gas exchange with the environment.
But there are times when a leaf takes on additional functions that are not characteristic of it. Then its structure changes dramatically, and we are again talking about modifications
.
1. If the stem of the plant is weak, then the leaf can perform a supporting function, clinging to surrounding objects. For example, the antennae of a pea.
2. In cacti, the leaves are modified into thorns. this form of the leaf allows you to drastically reduce the evaporation of water and protects against being eaten by animals.
Barberry spines are also modified leaves
3. Leaves-traps are typical for "predatory" plants. perhaps this is the most interesting and exotic modification. Oddly enough, the leaves change into "traps" not because the plant craves the blood of the victims, but because it grows on extremely mineral-poor soils. For example, our "compatriot" Rosyanka lives in peat bogs, where there is no soil at all.
So you have to get the minerals necessary for life from the bodies of various insects. And no one canceled photosynthesis in such plants. Therefore, their type of nutrition can be called mixotrophic.
In the Venus flytrap, the leaf halves, covered with thorns, can move and turn. when an insect lands on such a leaf, the halves slam shut, and the victim is trapped, where it is digested under the action of the digestive juices secreted by the glands of the leaf.
In the Pitcher (nepenthes) the leaves are in the form of a jug with a lid. Along the edges of such a jug is a bait in the form of nectar, and at the bottom - digestive juice. The walls of the jug are very slippery, and an insect that has fallen there will not be able to get out.
Video about carnivorous plants:
4. Sometimes the leaves surrounding the flowers and whole inflorescences are bright, conspicuous, such as the white or red covers of the cobs in aronnikovye (calla, anthurium) or the red, white and pink apical leaves of the poinsettia. They are easily mistaken for petals, while the true flowers of these species can be relatively small and inconspicuous.
Leaf modifications
Some plants change (and often quite significantly) the structure of the leaves for one purpose or another. Modified leaves can perform the functions of protection, storage of substances, and others. The following metamorphoses are known:
Leaf spines - may be derivatives of the leaf blade - lignified veins (barberry), or stipules (acacia) can turn into spines. Such formations perform a protective function. Spines can also be formed from shoots (see Modifications of stems). Differences: spines formed from shoots grow from the axils of the leaf.
Antennae are formed from the upper parts of the leaves. They perform a supporting function, clinging to surrounding objects (example: China, peas).
Phyllodes are petioles that take on a leaf-like shape and carry out photosynthesis. In this case, the true leaves are reduced.
Trapping leaves are modified leaves that serve as trapping organs of carnivorous plants. Catching mechanisms can be different: droplets of sticky secretion on the leaves (dew), vesicles with valves (pemphigus), etc.
Saccular leaves are formed due to the fusion of the edges of the leaf along the midrib, so that a bag with a hole at the top is obtained. The former upper sides of the leaves become inner in the bag. The resulting container is used to store water. Through the holes, adventitious roots grow inward, absorbing this water. Sack-shaped leaves are characteristic of the tropical liana Raffles dyschidia
Succulent leaves - leaves that serve to store water (Aloe, agave).
Similar organs (in plants)
The morphology of plants presents many examples of similar organs, i.e., such formations, the origin of which is different, but the functions are the same. So, the roots are similar to rhizoids, the spines are thorns, the seeds are spores. The similarity of functions often causes a great similarity of the external form. So, in the case of underdevelopment of leaves, the stems, which take over the work of assimilation, usually become flat and wide, acquiring a resemblance to leaves. Particularly interesting are the assimilating stems (cladodia or phylocladia) in Ruscus species. Here, the cladodia are so similar to leaves that for a long time there were disputes whether they were leaves or stems. In the same way, tubers are similar, whether they come from stems or roots, thorns and tendrils are similar, whether they come from leaves or from whole branches.
Homologous organs (Greek "homos" - the same) - organs that are similar in origin, structure, but perform different functions. Their appearance is the result of divergence. An example of homologous organs in animals is the forelimbs, consisting of the same bones, having the same origin, but performing different functions: in amphibians, reptiles, in most animals they serve for walking, in birds - for flying, in whales - for swimming, in mole - for digging the earth, a person performs the finest operations in labor process. In plants, the homologous organs are the fern growth, the primary endosperm of the pine ovule, and the embryo sac of the flowering plant. All of them are formed from spores, have a haploid set of chromosomes and carry a female gamete - an egg. But the fern growth is an autotrophic plant with archegonia. The primary endosperm of the pine is part of the ovule, and then the seed as a storage tissue. The formed embryo sac has eight cells, and only three of them take part in the development of the seed, the rest die off. Homologous organs indicate that in the course of adaptive evolution, traits undergo profound changes that lead to the formation of new species, genera, and larger systematic groups of animals and plants.
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Questions and answers for the exam in botany Biology. Morphology of plants. The structure of the root, Shoot, Stem, Leaf. Plants
This material includes sections:
Morphology of plants as a branch of botany. Tasks and directions of development
The main vegetative organs of a higher plant, their growth, branching, polarity and symmetry
Root, define. Root functions
Classification of roots by origin, in relation to the substrate
Structure of young root zones
Root systems and their classification. Types of root systems
Escape, define. Vegetative and generative shoots, elongated and shortened shoots
What organs are part of the shoot, and what functions do they perform?
Classification of shoots according to the nature of their location in space
Name the main types of shoot branching. Why is the sympodial type considered productive?
Stem, define. Stem cross-sectional shapes. The main functions of the stem
Morphology and classification of stem types
Kidneys and their types depending on the structure. Types and functions of kidneys depending on their position on the shoot
Types of kidneys by origin
Morphological diversity of the stem
Metamorphosis, define. root metamorphosis
Above-ground modification of shoots, their distinctive features, diversity and biological significance
Underground modification of shoots, their structure, diversity, biological significance, distinctive features
List, define. The structure and functions of the sheet
List, define. Variety of leaves and leaf formations
List, define. Forms of leaf blades, the main types of vein coriation of leaves of angiosperms
General characteristics and distinctive features of the sheet. The emergence of the leaf in the process of revolution
Leaf parts and their functions. The leaves are simple and compound. Edge character, general shape
Morphology of plates of simple leaves or compound leaves, nature of the edge, general shape
Morphology of simple leaf blades or compound leaflets
Leaf arrangement and its variants. The main patterns of leaf arrangement. Leaf mosaic
Leaf lifespan. Evergreen and deciduous plants. Biochemical and morphological preparation of plants and its biological significance
The structure of a plant seed. Morphological types of seeds
Conditions necessary for seed germination. Seed dormancy and its biological significance
Variety of leaves within a single plant. Layered categories of leaves. Heterophilia
Modifications of leaves or parts of leaves, their structure and biological significance. Examples of apalogous and homologous organs in plants
General ideas about the reproduction of higher plants. Comparative characteristics of different types of reproduction, their biological significance for higher plants
Methods of natural and artificial vegetative propagation of plants. The economic importance of vegetative propagation of plants
General characteristics of a flower. Organs and parts of a flower, their functions and formation in the process of flower ontogenesis
Very diverse in their structure and functions. Leaf modifications due to the fact that in the process of evolution, the leaves adapted to various climatic factors, depending on the growing conditions of plants.
In those plants that grow near water bodies, for example, in naturia, common reed, there is a so-called "lotus effect". This manifests itself as an extremely low wettability of the surface of the leaves of these plants. When water gets on the leaves or petals of these plants, spherical drops are formed, which flow down from the leaf, entrain dirt and dust, thereby cleaning the surface of the leaf blade. The appearance of this effect is due to the peculiarities of the microscopic structure of the leaf of plants of the genus Lotus.
Many deciduous trees have heavily indented leaves, such as the maple. This device allows you to withstand strong gusts of wind.
Plants growing in arid climates have many adaptations to survive in adverse conditions. This is a hairline on the leaves, which is able to retain moisture and prevent its evaporation. The wax coating on the leaf blade of some plant species performs the same function. The shiny surface of large flattened ficus leaves from the Mulberry family tends to reflect sunlight. These plants are native to Southeast Asia, where the climate is arid and hot. Also, almost all types of cacti are adapted to long dry periods. Therefore, these plants have leaves transformed into spines to reduce water evaporation and protect against pests. In cacti, the function of photosynthesis passes from leaf to stem, which, together with a decrease in leaf size, prevents moisture loss. In those plants that natural conditions grow in well-lit places, such a device has developed on the leaves as translucent windows that act as a filter of light before it reaches the inner layers of the leaf. This is what happens in fenestraria. In the fleshy succulent leaves of aloe, stonecrop accumulates water, which the body of the plant spends with a lack of moisture during external environment. In the same way, onion leaves have transformed into a bulb, which helps the plant retain water and nutrients.
The leaves of some plants have teeth along the edges. This adaptation is necessary, as it increases the severity of the processes of photosynthesis and transpiration (during which the temperature in these departments decreases). This leads to condensation of moisture on the points of the leaves and the formation of dew drops.
The leaves of many plants are transformed during evolution in order to protect the plant from destruction by other living organisms. So, pheromones, poisons, aromatic oils can be produced in the leaves, for example, in eucalyptus. And the leaves of other plants include crystallized minerals, which repels herbivores.
In peas, ranks, some types of peas, antennae appeared from leaves transformed in the process of evolution. Such a device serves to enhance the supporting function of the plant stem. The plant, clinging to the supports with its antennae, rises up, carrying the leaves to the light.
Modified leaves of some plants have been transformed into petals for better pollination by insects that are attracted to these parts of the plant's body. And the transformation of leaves into false flowers and cover leaves allows you to replace the missing organs in milkweed.
Sundew and pemphigus turned into predatory plants due to the transformation of the leaves, which became trapping devices for insects that the plants feed on.
Thus, due to the modification of leaves, plants adapt to existence in adverse environmental conditions.
The leaf is one of the most plastic plant organs. In the process of adaptation to environmental conditions, the entire leaf or part of it may change its main function. This leads to qualitative changes in the external appearance and internal structure of the leaf, that is, modifications or metamorphoses of the leaf occur (Fig. 32).
spines
This modification is characteristic of plants living in dry and hot climates, although they often occur in plants of other climatic zones. Spines reduce transpiration and protect plants from being eaten by animals.Metamorphosis of the entire leaf into a spine is characteristic of cacti. In many astragalus, sainfoin, the rachis of a complex leaf turns into a thorn, in white acacia - stipules.
These are filamentous formations, sensitive to touch and adapted for climbing. In vetch, lentil, pea, the upper part of the rachis and several upper leaves are converted into a tendril. In the leafless rank, all leaflets are reduced, and the rachis is the only antennae (stipules take over the function of photosynthesis.
trapping devices
They are found in plants growing on swampy, peaty, mineral-poor soils. With the help of trapping devices, the sundew in the middle lane, the Venus flytrap in North America, and the Nepenthes in tropical Asia use organic food rich in nitrogen and phosphorus, digesting animals. The structure of the trapping devices is different (Nepenthes pitchers, Venus flytrap traps, sundew leaves), but they are all capable of trapping and digesting insects and other small animals with the help of enzymes secreted by special digestive glands.
Rice. 32. Sheet modifications:
1 - tendril of the leafless rank; 2 - thorn of milkweed shining; 3 - trapping apparatus of Nepenthes.
leaf fall
When the leaves reach the limiting size, aging processes begin in them, leading to the death of the leaf. As the leaves age, the intensity of photosynthesis and respiration decreases, and the content of protein nitrogen and RNA in tissues decreases. The processes of decay, rather than synthesis, begin to predominate. Organic matter drains from old leaf tissue. At the same time, some salts accumulate in the leaves, such as calcium oxalate crystals.
A sure sign of leaf aging is a change in its color. Leaves lose their green color as a result of chloroplast degradation. Yellowing and reddening of the leaves is associated with the accumulation of carotenoids and anthocyanins in them.
In monocots and herbaceous dicots, the leaves gradually die off and collapse, remaining on the stems. At trees and shrubs
l
Rice. 33. Formation of a separating layer: 1 - wood; 2 - core; 3 - bast; 4 - periderm; 5 - separating layer; 6 - conductive beam; 7 - leaf petiole.
Leaf fall is an important adaptation of plants to reduce moisture evaporation. It also protects plants from mechanical damage in the winter.
Plant organs, in addition to the main ones, can perform some other functions. Often in such cases, modified organs are formed. Consider first of all the modifications of shoots (Fig. 1).
The value of modified shoots
modified underground shoots
Rhizome(couch grass, gout, ferns) - an underground shoot with scaly leaves covering the axillary buds (Fig. 1). The apical bud provides the growth of the rhizome, and the axillary - its branching. Both those and others can give rise to above-ground leaves and shoots.
tubers (potato, Jerusalem artichoke)- growth at the end of a long underground shoot calledstolon. There are usually no axillary buds on the stolon, and on the tuber they form the so-calledeyesfrom which new plants can develop. The main function of the tuber is the supply of nutrients (starch, etc.) (Fig. 1).
Bulb(onion, tulip) - an underground shoot with a shortened stem and succulent leaves to store water and nutrients (Fig. 1). Bulb base - bottom is a flattened stem. Leaves, called juicy scales, depart from it in the middle part. They store nutrients. In the center of the donut there is an apical bud, and in the axils of the scales there are axillary buds. They can give rise to aboveground organs or new plants. Outside, the bulb is covered with dry scales, which are also modified leaves (onions, lilies, hyacinths).
Corm(gladiolus) - an overgrown stem, covered with dry scales on the outside (gladiolus). Function: supply of nutrients (Fig. 1).
Modified above-ground shoots
Adapting to environmental conditions, ground shoots are modified in plants. Often, it is not the whole shoot that undergoes modification, but one of its organs.
Phyllocladia(butcher's needle, asparagus) - flattened leaf-shaped stems that perform the function of photosynthesis. Often these stems completely replace the leaves. In this regard, the cells of the outer layers of the cortex, located directly under the transparent epidermis, turn green, as they contain chloroplasts. Phyllocladia differ from leaves by the presence of buds on them, and sometimes even flowers and fruits (Fig. 4).
spines(hawthorn) and antennae(grapes) - modified side shoots (Fig. 6). Formed in the axil of the leaf, and if the leaf dies - above the leaf scar.
Mustache(strawberry) - long creeping shoots without leaves, which serve for vegetative reproduction (Fig. 1).
Modified shoots also include:
bud- rudimentary vegetative or generative shoot;
head of cabbage- strongly overgrown kidney;
flower- a shortened generative shoot with limited growth, intended for seed propagation of plants;
cone- a modified short shoot of conifers, intended for seed propagation of plants.
Leaf modifications
Leaf changes are often observed.
The meaning of modified leaves
Leaf spines serve to protect the plant from being eaten or mechanically damaged by animals. Similar spines in barberry are modified lignified veins of the former leaf plate. In white acacia and caragana, paired spines are formed in place of stipules and are located at the base of the leaves.
The prickly pear cactus, in addition to the hard "classic" spines, has small, serrated, very fragile spines - glochidia, which are easily separated from the shoot and cause pain (Fig. 12).
Cactus spines are modified bud scales that serve primarily to shorten transpiration(evaporation of water by leaves) in dry conditions. But in addition to sharp thorns, cactus leaves can be modified into feathery "hairs" that entangle the entire plant. Their main function is to protect the cactus from direct sunlight and trap dew (Fig. 13). Most often, spines lack chloroplasts and are unable to photosynthesize.
Rice. 12 Fig. thirteen
tendrils of leaf origin are characteristic of representatives of the legume family. Their main function is to fix the plant on a support.
In some cases, the leaves take on a storage function. In this case, the mesophyll grows, its inner layers do not receive light and do not photosynthesize, but nutrients or water can accumulate in them (fam. Crassula) (Fig. 14).
They have a leafy origin. juicy storage scales lily bulbs (Fig. 1).
Tropical liana dischidia has unusual bag-shaped leaves, formed during the fusion of the edges of the sheet plate. The leaves serve to store rainwater. Through the upper hole, not only water enters the leaf, but also the adventitious roots of the vine, which absorb water (Fig. 9, 10).
root modifications
Root modifications are often caused by strengthening one of their main functions. Unlike tubers of stem origin, they do not have buds.
The meaning of modified roots
Storage function (root crops, root tubers (root cones)).
Root crops (carrots, turnips, beets) - growth of the upper part of the root, into which the lower part of the stem or the entire shortened shoot is drawn (Fig. 15).
Root tubers, or root cones, (dahlia, sweet potato) - growth of lateral roots (Fig. 16).
The aerial roots of epiphytic plants (Fig. 17) serve to absorb air moisture, since they are unable to obtain nutrients from the soil.
In orchids, such roots are covered with several layers of dead cells, forming a spongy surface. Such roots can absorb water during rain and dew, as well as absorb it from the air in the form of water vapor. When exposed to light, their cells often contain chloroplasts and take over the function of photosynthesis.
Supporting roots, or stilted roots,(banyan, corn (Fig. 18)) - adventitious roots in a number of large trees in the tropics are formed on lateral branches high above the ground. They support heavy lateral branches and also serve as a source of mineral nutrition for them.
Rice. 18 Fig. nineteen
respiratory roots- these are lateral roots that do not grow down, as it should be for the roots, but up (Fig. 19). They form on waterlogged soils, where the roots often lack oxygen for normal functioning. Reaching a non-flooded surface, they form holes at the ends open to the air. Inside such roots, an air-bearing parenchyma is formed with large intercellular spaces connected along the entire length of the root. Through them, oxygen diffuses deep into the root system, providing the root cells with the opportunity to receive a sufficient amount of energy.
Lesson summary drawingin senior group on the topic: « Who I want to be»
(using information– communicativetechnologists)
Target: teach children plot drawing, drawing a person.
Wadachi:
Continue learning to draw people in motion.
Learn how to compose.
Continue to consolidate children's knowledge about the types of professions.
Develop compositional skills (draw on the entire sheet of paper, convey proportional and spatial relationships between objects).
Materials:
Gouache paints;
brushes 2-3 sizes;
sheets of paper (pre-tinted);
jars of water;
paper and cloth napkins;
illustrations depicting people of different professions (selection of illustrations for display using a multimedia projector).
Lesson progress:
The teacher reads the poem "Professions" to the children:
Maybe not enough knowledge
But you can dream!
I'll probably be a doctor
I will heal people!
I will travel everywhere
And save sick children!
Soon I will be a soldier
Or just a pilot - ace!
Like an ordinary hero
I will protect you!
ballerina and singer
I have always dreamed of becoming!
To dress up nicely
Sing and dance for you!
I am a famous artist
I will definitely.
I'm interested in drawing
Very exciting!
I am a school teacher
I will give knowledge to children!
The kids will be happy with me
I tell you for sure!
Well, I'll be back here!
Affectionate, attentive
And always responsive
I will become an educator!
Guys, let's play with you!
Let's remember what other professions there are, except for those that sounded in the poem.
Game: "Name the profession."
(The teacher, in turn, throws the ball. Thatwhoever catches the ball names one of the professions.If the child finds it difficult to answer, the teacher makes a riddle, helps to answer).
For example: « Poems are riddles about professions.
A traffic light is flashing for me, The insidious fire will win, He knows that I am ... The one whose name is ... ( Chauffeur.) (Fireman)
Before work, he is a hunter, Furniture, bread and cucumbers Day-to-day with a planer ... They sell us ... ( A carpenter.) (Sellers)
The patient will not solve the problems, He knows for sure the kids: He will treat all the sick ... They feed deliciously ... ( Doctor.) (cooks) A stretched canvas, paints, a tripod - I put it yesterday. She paints a picture from nature ... Five injections ... ( Artist) (Nurse.)
He walks around the area with a heavy bag, Every resident in the house knows - He puts letters to us in a box ... He built this house ... ( Postman) (Builder.)
Well done! You have named so many professions. And now let's draw people of these professions.
We will draw with paints (gouache). But first, let's see what kind of pictures you can draw.
(The teacher shows illustrations on a multimedia projector. Drawing children's attention toappearance, position of the body, position of the arms - to the sides, bent, raised to the top.)
- Do not forget about the palette, what colors need to be mixed to get pink or flesh color for painting the human body.
The kids get to work. As needed, the teacher helps those children who need help.
Summary of the lesson.
What wonderful pictures you have drawn.
Let's collect them in one big book, which we will call "Who I want to be"
(The teacher compiles a book, supplementing it with verses that the parents selected).