Modified organs. Botany. Metamorphoses of roots, sheet. Modifying leaves: causes and examples in nature. General ideas about the reproduction of higher plants. Comparative characteristics of different types of breeding, their biological significance for higher
1. Simple leaves have one sheet plate, which can be different forms: a heart, like lilac, oval-figured, like an oak, stretched out with sharp corners, like a cherry.
2. Complex leaves have several leafy plates. They are attached to a shared tub - Rakhisu. Such leaves were formed in ash, chestnut, hawthorn, raspberries, rowan. Complex leaves are three types:
· three-grained - consisting of three plates, like the same raspberry, clover or acids;
· palcounty - consist of several plates diverging from a single center, resemble palm, although the number of "fingers" can be different: chestnut, lupine.
· peristent leaves - leaflets with symmetrical pairs are located on both sides of Rakhis, like acacia, walnut. If the complex sheet ends with one unpaired leaf on top - this is a unpaired sheet type (rowan, ash). If at the end of the "superfluous" sheet, there is no password-sized type (peas, rosehip).
A variety of leafy plates
Nature has created a huge variety of sheet forms. Types of plants within the same kind may have a sheet of completely different shape, as, for example, in ficuses: compare figs and ficus of Benjamin. Let's look at the examples of different forms of the sheet on two signs - what is the common form of a sheet plate and which abis has its edge.
Form of plates
1. Rounded (SENPOLIA, water lily, aspen).
2. Ovoid (nettle, ram, jasmine, coffee tree).
3. Linear (powder, wood, wheat, amaryllis, gladiolus).
4. Wireless (Lily of Lily, Anthurium, Host, Aspidistra).
Leaf Plate Edge Shape
1. One piece (lilac, plantain).
2. Gear (apple tree, cuff).
3. Pillar (nettle, rowan, aspen, sick).
4. Loose (monster, maple).
5. Located (Budra, Oak).
Residential leaf plate
Fancy lines on the surface of the sheet - sometimes thin, whimsically confusing, sometimes thick and few are veins. Through alkalis, there is both uptring and downward flow of water and trace elements. It is possible to clearly see the dwelling on the so-called skeleton leaves: they are sold in the departments of dry flowers, in nature are found in late autumn, and you can do them yourself, deleting the top layers of the sheet. The jilling is different types.
1. Curly or mesh - in the center of the sheet there is one main dense vein, the entire sheet plate is covered with thin interlaced veins (oak, nettle, aspen).
2. Palp - several central residents diverge to fan, small (sharply, cuff, cuff) are already departed from them. The first two types of housing are observed in bicycle plants.
3. Parallel - large straight lines go from the base of the sheet to its tip (millet, wheat, iris).
4. Arc - alkali is curved by arcs, except for direct Central (Lily of Lily, Plantain). The third and fourth grade type is observed in monocotional plants.
Modifying leaves
In the process of evolution, the sheet experienced many nature experiments, changing its appearance, adapting to the surrounding conditions. Then a variety that we now observe - the result of natural selection. We list the main modifications.
1. Spines - cacti engaged in moisture condensation.
2. A mustache - in pea and ranks allow the plant "crawling", clinging for any support.
3. Candy adaptations of insectivore plants, for example, Genlisia and Rosyanka.
4. Filodia - have a born flat paper with photosynthesis function, sheet plate reduced (Australian acacia).
5. Scales are small, underdeveloped leaves, like Lolannysh, Pea, and also on the rhizome of drinking.
6. Burnt kidney scales - in the winter kidney majority plants.
7. Bulk scales of bulbs and clubnellukovits (lily, garlic, crocus, a non-freeman).
8. Juicy scales of bulbs (lily, tulip).
9. Meaty juicy leaf (aloe, agawa).
The main functions of the leaves can be called photosynthesis and evaporation of water. To perform these functions most effectively, the sheet must have a plate shape, that is, to have a large surface and be thin. These are the leaves of most plants. However, in some plants, the leaves in the process of evolution were changed (changed) and became unlike ordinary leaves. The reason for this phenomenon is that the leaves began to perform other functions that are not associated with photosynthesis and evaporation.
The leaves of a row of plants of dry habitats were modified in spinys. Such leaves, on the one hand, almost do not evaporate water, on the other hand, protect plants from eating animals. An example of plants of desert places with spines are various cacti. Photosynthesis in them proceeds in the thick stem cells located closer to the surface. Also in the stem is water. Thus, the leaves have lost their main functions (photosynthesis and evaporation) in spines (photosynthesis and evaporation), but a protective function began to perform in replacements.
Cut leaves can be observed not only in plants deserts and semi-deserts. The barbs are at Barbaris, rose bushes, rosehip, etc. However, these plants are not all the leaves are modified in the spines, but only some. At the same time, the function of the barns here is the same as cacti - protection against eating animals.
In the photo you can see barbs - modified rose rose leaves
The leaves of other plants of arid habitats adapted to the lack of moisture in a different way. So aloe and agave leaves modified in thick and juicy formations in which water is stored. And in order to reduce evaporation, such leaves are covered with a wax, hairs, have less dust. In this case, the leaves were modified in such a way that they did not lose their basic functions, while acquired an additional stocking of water.
There are plants that have leaves modified in mustache. With these unts, the plant clings to the support and is held in a vertical position. An example of plants with the mustache are peas, rank, vika and other legumes. Pea in the mustache turned the tops of the leaves.
In nature there are insectivorous plants. Their leaves are modified in peculiar cutting devices . When the insect sits on a leaf of Rosyanka Plants, it is glued to it, since the sheet is covered with hairs excreasing a viscous mass. After that, the hairs and the leaf itself turns. Inside the resulting cavity, the insect is digested due to the enzymes released by the sheet. From the insect Rosanka absorbs organic substances rich in nitrogen. It is precisely because of the lack of nitrogen and other trace elements in places of their habitat, the leaves of Rosyanka acquired such a specific function.
Another modification of the leaves are schey. At the same time, scales are different, because they perform various functions. For example, onion in the bulb, the leaves turned into juicy scales, in which the supply of nutrients is postponed. Other scales cover the kidneys. In this case, they perform a protective function.
Plant organs other than the mains can also perform some other functions. Often, in such cases, modified organs are formed. Consider first of all the modifications of shoots (Fig. 1).
The meaning of modified escapes
modified underground shoots
Rhizome (drinking, sick, ferns) - underground escape with scratched leaves, covering styling kidneys (Fig. 1). The top kidney provides rising growth, and the stubby is its branching. And those and others can give the beginning of overhead leaves and shoots.
Tubers (Potatoes, Topinambur)- growing at the end of a long underground escape calledcolumn. There are usually no stubby kidneys on the column, and they form the so-calledeyesFrom which new plants may continue to develop. The main function of the tuber is the supply of nutrients (starch, etc.) (Fig. 1).
Bulb(onions, tulip) - underground escape with shortened stem and juicy leaves for the reserve of water and nutrients (Fig. 1). The base of the bulbs - damec - It is a flattened stem. From him in the middle of the leaves, called juicy scales. Nutrients are inhibited in them. In the center of the Donets there is a top kidney, and in the sinuses scales - stubborn kidneys. They can give the beginning of the above-ground organs or new plants. Outside the bulw is covered with dry scales, also representing modified leaves (onions, lilies, hyacinths).
Corm (Gladiolus) - Ombreted stem, outside covered with dry scales (gladiolus). Function: Nutrient stock (Fig. 1).
Modified overhead shoots
Adjusting to the conditions of the medium, the plants are modified by terrestrial shoots. Often modifications are not a whole escape, but one of its organs.
Fillocladium (Ilitian, Asparagus) - flattened sheet stems that perform the function of photosynthesis. Often such stems completely replace the leaves. In this regard, the cells of the outer layers of the cortex, which are directly under the transparent epidermum, are green, as they contain chloroplasts. Filloclands differ from the leaves by the presence of kidney on them, and sometimes even flowers and fruits (Fig. 4).
Spinys (hawthorn) and mustache(Grapes) - modified side shoots (Fig. 6). They are formed in the top of the sheet, and if the sheet dies away - above the leaf scar.
Mustache(Strawberry) - Long creeping shoots without leaves, which serve for vegetative reproduction (Fig. 1).
The modified shoots are also:
bud - relevant vegetative or generative escape;
kochan - severe kidney;
flower - shortened generative escape with limited growth, intended for seed reproduction of plants;
cone- A modified shortened coniferous escape, intended for seed reproduction of plants.
Modifying leaves
Often there are modifies of leaves.
The value of modified leaves
Sheet spines serve to protect the plant from either mechanical damage to animals. Such spines at Barbaris are modified weathered veins of the former sheet plate. White acacia and caragans, pair barbs are formed at the site of horses and are located at the base of the leaves.
At the schoom cactus, in addition to the hard "classic" barns, there are small briggble spines - glochidiawhich are easily separated from escape and cause painful sensations (Fig. 12).
Cacti barbs are modified renal scales that serve primarily to reduce transpiration (evaporation of water with leaves) in the arid conditions. But besides acute spikes, the leaves of cacti can be modified into camp "hairs" entangling all the plant. The main function is the protection of cactus from direct sunlight and dew collection (Fig. 13). Most often, the spines are deprived of chloroplasts and are not capable of photosynthesize.
Fig. 12 Fig. 13
Mustache Sheet origin is characteristic of representatives of the legume family. The main function is fixing the plant on the support.
In some cases, the leaves take the spare feature. In this case, the growth of the mesophyll occurs, its internal layers do not receive light and not photosynthesize, but nutrients or water (seats are thick) (Fig. 14) can accumulate in them.
Leaf origin have juicy sparkling schellowi Lilywich bulbs (Fig. 1).
Tropical Lian Dyshidia has unusual basching leavesFormed when the edges of the leaf plate edges. Leaves serve to storing rainwater. Through the upper hole in the sheet, not only water, but also the apparent roots of the lianas, absorbing water (Fig. 9, 10).
channel modifications
Channel modifications are often caused by the strengthening of one major functions. In contrast to the tubers of stem origin, they do not have a kidney.
The meaning of the modified roots
Flooring function (root, root tubers (root cones)).
Roots (carrots, turnips, beet) - the growth of the upper part of the root, into which the lower part of the stem or the entire shortened escape is dragged (Fig. 15).
Root tubers, or root cones, (dahlian, batt) - the growth of the side roots (Fig. 16).
Air roots of epiphytic plants (Fig. 17) are used to absorb air moisture, since they do not have the ability to obtain nutrients from the soil.
Orchids have such roots 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 air in the form of water vapor. While in light, their cells often contain chloroplasts and take on the function of photosynthesis.
Reference roots, or roots-stuff,(Banyan, Corn (Fig. 18)) - Pressure roots in a number of large trees in the tropics are formed on the side branches high above the ground. They maintain heavy side branches, and also serve them with a source of mineral nutrition.
Fig. 18 Fig. nineteen
Respiratory roots - These are the side roots that grow not down, as it should be rooted, and up (Fig. 19). They are formed on wetlands, where the roots for normal functioning often lack oxygen. Reaching an uneplicable surface, they form at the ends open into the air holes. Inside such roots, air-capable parenchyma is formed with large interclausers connected along the entire length of the root. Oxygen diffuses on them deep into the root system, providing roots with the capabilities to obtain a sufficient amount of energy.
Sheet is one of the most plastic organs of the plant. In the process of adapting to the conditions of the habitat, the entire sheet or part can occur the main function. This leads to qualitative changes in the appearance and the inner structure of the sheet, that is, modifications or metamorphosis of the sheet arise (Fig. 32).
Spinys
This modification is characteristic of plants living in a dry and hot climate, although they often arise in plants of other climatic zones. Spines reduce transpiration and protect plants from eating animals.Metamorphosis of the entire sheet in the barboard is characteristic of cacti. Many Astragalov, Espartzets in the barn turning the RAHIS of a complex leaf, in White Acacia - Highlights.
This is a filamental formation sensitive to touch and adapted for climbing. At the wiki, lentils, peas in the mustache are converted to the upper part of Rakhis and several upper leaves. The rank of alert all the leaflets are reduced, and Rahis is the only mustache (the function of photosynthesis takes advantage.
Cutting devices
There are plants growing on swampy, peat, poor minerals soils. With the help of Lyazanka devices in the middle strip, Veinele of the Mukholovka in North America, nonentures in tropical Asia use organic food rich nitrogen and phosphorus, digesting animals. The structure of the adiputs of the devices is different (nnevitchikov's lines, veneree traps, the leaves of Rosyanka), but they are all able to capture and digest insects and other small animals with the help of enzymes allocated by special digestive glands.
Fig. 32. Sheet modification:
1 - the mustache of the rank is noble 2 - Brilliant prickly brilliant; 3 - Lovely non-tape apparatus.
Leaf fall
Upon reaching the leaves of limit sizes, the processes of aging begin, resulting in leaf death. As aging in the leaves, the intensity of photosynthesis and respiration is reduced, the content in the tissues of protein nitrogen and RNA decreases. The decay processes are beginning to prevail, not synthesis. Organic substances are leaving the old sheet tissues. At the same time, some salts accumulate in the leaves, such as calcium oxalate crystals.
A faithful sign of aging sheet is to change its coloring. Leaves lose green color as a result of chloroplast degradation. The yellowing and redness of the leaves is associated with the accumulation of carotenoids and anthocian in them.
Odnocolnaya and herbaceous bombing leaves gradually die and destroy, staying on the stems. In trees and shrubs
l.
Fig. 33. Education separating layer: 1 - wood; 2 - core; 3 - Louba; 4 - Periderma; 5 - separating layer; 6 - conductive beam; 7 - Sheet Packer.
Leaf Fall is an important adaptation of plants to a decrease in moisture evaporation. He also protects plants from mechanical damage in winter.
| Modifying organs of plants - escapes, leaves, roots |
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| Modifying underground escapes |
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| Tuber | Thicped meaty escape - formed at the ends of the columns. Eyes - kidneys | Potato, Topinambur |
| Stolon | Slim bleached underground escape, at the end of which tubers are formed | Potatoes |
| Bulb | Overhead or underground shortened escape with sheet-like dry or juicy leaves and shortened stem - in Don. | Onions, garlic, tulip |
| Corm | Externally resembles a bulb, but its scratched leaves are not in stockpit; They are dry and film, and spare substances are deposited in a thickened stem part. | Saffron, Gladiolus |
| Rhizome | Underground Escape of perennial plants, which looks like root. Rhizome has nodes and interstices. In the sinuses of scratch-shaped leaves - sleeping kidneys | Dress, Lily of Lily, Iris, Nerv |
| Modifications of overhead escapes |
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| Spinys | Solid sharp shoots without leaves or with underdeveloped leaves. | Hawthorn, apple tree, sea buckthorn |
| Counters | (Domestic name - "mustache") Horizontal creeping shoots that promote the reproduction of the plant. Each time there are outlets with apparent roots. | Strawberry, lounge creeping |
| Mustache | A thin tenacious escape that comes out of the sinuses of the sheet. | Grapes, cucumber |
| Succulent shoots | Thick meaty escape adapted for accumulation and maintaining a large amount of water. | Cacti, Mokhokha |
| Modifying leaves |
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| Kolyuk (in her sickness there are kidney or escape) | Protection | Cactus, Barbaris |
| Cutting devices Insectivorous plants | Capture and digesting insects | Rosanka, Venus Mukholovka, Nevenzen |
| Succulent leaves - juicy, fleshy water leaves | Reservewater - Leaves have a dense wax cuticle and special moisture-proof cells | Claws, Agave, Aloe |
| Tendril (located on the site of the sheet) | Attachment to the support | Peas, ranks |
| Schey - Leaves devoid of chlorophyllthin | Protective function | Onion |
| Juicy scales | Power supply of nutrients | Onion |
| Channel modifications |
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| Flashing roots | The laying of spare substances in the main root leads to educationroot and in lateral and extra roots -root clubs ; Roots and root tubers servecreate nutrients | Carrots, Radree, Beets (root), dahlias (root tubers) |
| Air roots | Develop on the above-ground organs of plants and ensure the absorption of rainwater or absorb water from a very humid atmosphere | In tropical epiphytes (orchid, bromelievy) |
| Respiratory roots | Between the root cells are air cavities, roots grow up, rise above the surface of the soil and provide air inflow underground parts of the plant | In tropical plants growing on marshy soils (for example, swamp cypress) |
| Roots - suckers | At the end, go into the sucker - penetrate into conductive tissues of another plant and sucks from it nutrients | |
| Roots - bars | Additional minor roots that develop on the bottom of the stem and ensure the attachment of the plant to other plants, walls and rocks | Liazing Lian, Fikuses, Ivy |
| Support roots | Additional wandering roots that grow out of stems down and fix in soil. Side Board-like roots that are adjacent to the trunk and help him support the crown | Fikuses (Banyan), some palm trees, corn. In tropical trees, weakly expressed at beech, elm |
Homologous and similar organs.
The plants distinguish homologous and similar organs.
Homologous organs have the same origin, but may differ in the form and performed functions, for examplebully and rhizische .
Similar organs The opposite, externally similar, perform the same functions, but have a different origin, for examplebarberry straps and hawthorn .
roots
Examples of similar organs
Morphologyplantspresentslotexamplessimilar organs , t.. e.. sucheducation, originwhichvarious, butfunctionsthe same. So, roots similarricoidam , spinys - spike , seeds - spots .
In plantshomologous organs There are a fern incense, primary endosperm of a pine, germinal bag of a flowering plant. All of them are formedfrom spores , have a haploid set of chromosomes and carry a female game - an egg cell. But the stroke of the fern is a car-flow plant with Archeganius. Primary endosperm pine is part of the nephery, and then seed as a flat tissue. A shaped germs bag has eight cells, and only three of them take part in the development of the seed, the rest die. The homologous authorities suggest that during the adaptive evolution, signs undergo deep changes, which lead to the formation of new species, childbirth and larger systematic groups of animals and plants.
Homologous The authorities are called such that have the same origin, but the structure and functions of them are different (for example,petals Flower and Mustache Pea There were made of leaf, and their external structure and functions are different).
CactusBarberry
Wild apple tree
Wild pear
Sea buckthorn
Hawthorn
Note:
Spines should not be mixed with spikes existing on stems of rosehip, gooseberry, raspberry.The spikes differ from the barns of smaller sizes,these are grown surface tissues of the stem, and not by modifying any organ.
Rhizome it usually does not carry green leaves, but, being escaping, retains a metairer structure. The nodes are highlighted either by sheet scars and remnants of dry leaves, or by alive scaped leaves, also in nodes there are stubborn kidneys. According to these signs, rhizome is easy to distinguish from the root. As a rule, pressing roots are formed on rhizome; From the kidneys grows the side branches of rhizomes and overhead shoots
