Plants with a small number of stomata. The number of stomata in some plants

1.7 Number of stomata and their distribution on the leaf

The number of stomata on the leaf surface ranges from several hundred to 1000 per 1 mm² of leaf surface. Most herbaceous plants have stomata on both sides of the leaf. Many shade-tolerant plants have stomata only on the underside of the leaf. This same feature is characteristic of most tree species (birch, oak, poplar, etc.). Despite the fact that stomata make up a very small part of the leaf area (the area of ​​their openings in the open state is about 1%), the release of water vapor through open stomata occurs unhindered. According to Stefan's law, the diffusion of water vapor on surfaces is proportional to their diameter, not their area. In this regard, evaporation from a vessel with many holes occurs faster than from a vessel with one large hole. For this, however, one condition is necessary, namely, the small holes must be located at a certain distance from each other. The location of the stomata in the leaf epidermis corresponds precisely to this.

Evaporation from the edges of the holes occurs faster than from their middle. In the middle of the hole, the evaporating particles have a greater influence on each other, and evaporation slows down. On this basis, the greater the ratio of the perimeter to the area of ​​the hole, the more intense the diffusion of guillemots will occur, since this ratio is greater, the smaller the diameter of the hole.

From the above it follows that the overall rate of diffusion through a finely perforated membrane will occur at almost the same rate as from a vessel without a membrane. The latter can be clearly seen from the diagram in Figure 4.

Figure 4. Scheme of evaporation of water vapor from an open vessel (1) and through a finely perforated membrane (2).

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annotation scientific article on biological sciences, author of the scientific work - Yulia Vitalievna Belyaeva

This research devoted to the study of the water regime of Betula pendula Roth. The assessment was carried out based on the results of the study quantitative indicators of stomata leaf blades. The analysis was carried out in the summer. It was found that at the beginning of summer the water-holding capacity is high, and at the end of summer, closer to autumn, it is low. The data obtained shows strong addiction the number of stomata from air pollution in the habitats of the species under study.

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This research work is devoted to the study of the water regime Betula pendula Roth. The evaluation was conducted according to a study of quantitative indicators of stomata of the leaf blades. Analyzing was conducted in the summer. It was found that in the early summer high performance water-holding capacity, and at the end of the summer, closer to the fall low. These data show a strong dependence of the number of stomata on air pollution habitats studied species.

Text of scientific work on the topic “Results of a study of the number of stomata of leaf blades of Betula pendula Roth. , growing under conditions of anthropogenic influence (using the example of G. O. Tolyatti)"

Terrestrial ecosystems

RESULTS OF STUDYING THE NUMBER OF STOMATA OF LEAF PLAMES OF BETULA PENDULA ROTH. GROWING UNDER CONDITIONS OF ANTHROPOGENIC INFLUENCE (BASED ON THE EXAMPLE OF THE G.O. TOGLYATTI)

© 2015 Yu.V. Belyaeva

Institute of Ecology of the Volga Basin RAS, Togliatti Received 01/12/2015

This research work is devoted to the study of the water regime of Betula pendula Roth. The assessment was carried out based on the results of a study of quantitative indicators of the stomata of leaf blades. The analysis was carried out in the summer. It was found that at the beginning of summer the water-holding capacity indicators are high, and at the end of summer, closer to autumn, they are low. The data obtained show a strong dependence of the number of stomata on air pollution in the growing areas of the species under study.

Key words: water regime, quantitative indicators of stomata, leaf blades, Betula pendula Roth., stability of development, anthropogenic, biotic and abiotic factors.

INTRODUCTION

The Tolyatti urban district is one of the most developing centers in Russia. The main sources of air pollution are the largest enterprises in the automotive industry, petrochemicals, production of chemical fertilizers and building materials, thermal power plants and boiler houses, road and rail transport with a high density of traffic flows, and a river port. Additional factors include population growth and intensive development of residential and administrative buildings. Pollution assessment atmospheric air The city of Togliatti revealed that the most polluted atmosphere is the Central district (2 and 1.3 times higher than permissible), followed by the Komsomolsky district (2 and 1.1 times higher than permissible), then the Avtozavodskoy district (1.9 times), the suburban area is minimally polluted (according to the Federal State Budgetary Institution Privolzhskoye UGMS, 2015).

The high degree of pollution inherent in such cities leads to the weakening of some types of woody plants, their premature aging, decreased productivity, damage by diseases and pests, drying out and death. Betula pendula Roth, is a common tree species in urban plantings

For resistant woody plant species

characterized by such features as a larger number 1 2

stomata per 1 mm of leaf surface; shorter duration and degree of openness during the day; greater thickness of the cuticle and the presence of additional integumentary formations; smaller thickness and ventilation of spongy parenchyma; a smaller ratio of the height of the palisade tissue to the height of the spongy tissue.

Belyaeva Yulia Vitalievna, assistant, [email protected]

Required Scientific research to study the mechanisms of adaptation, growth and development of woody plants, as well as their survival rate under the conditions of negative anthropogenic impact of industrialized cities. Currently, work in the field of environmental monitoring is relevant, which includes chemical, physical and biological methods for assessing the quality of the environment. We conduct a comprehensive ecological and biological assessment of the state of urban woody plants. Using an ecological and biological assessment, it is possible to obtain specific data on the state of green spaces in an urban environment subject to anthropogenic and climatic influence. In the Samara region, the summer of 2010 was distinguished by three months of lack of rain, extreme dry air and, as a result, numerous fires that destroyed many hectares of precious forest. Heat, temperature over 40°C, plus 45°C in the shade, plus 70°C on the soil, dry soil at a depth of 3-6 m, constantly scorching sun, as well as reflected heat and light in the city. These factors influenced the stands of Betula pendula Roth. growing in the city and suburbs. Over the following years, a fact emerged indicating that individuals of Betula pendula Roth. continue to suffer and wither away. Therefore, the problem of the effectiveness of this type of plant and measures to restore Betula pendula Roth plantings is particularly acute. or replacement with other more sustainable species, as well as stabilization of the environmental situation in the city.

MATERIAL AND METHODS

It is known that the processes of water evaporation (transpiration) and gas exchange in plants occur through stomata. Atmospheric pollution affects the stomatal apparatus of plants, which leads to

disruption of stomatal functions and plant death. By counting the number of stomata on leaf blades and comparing them with the control, you can obtain data indicating the state of the plant, its adaptive ability, and also identify areas of increased pollution.

The study areas are located in the continental climate zone of temperate latitudes with characteristic arctic and tropical air. In winter this manifests itself in the form of severe frosts, and in summer - sharp fluctuations in temperature during the day. During the year, the average monthly air temperature in Togliatti varies from +20.7°C in July to -11°C in January.

The purpose of the study was to assess the condition of Betula Pendula Roth, in conditions of anthropogenic pollution of the city of Tolyatti, using the anatomical and physiological characteristics of leaf blades.

The research was carried out in 2013-2014. at five experimental sites in two administrative districts in various types of plantings. In the Avtozavodsky district these are the Industrial Zone and Victory Park. In the Central District this is Banykin Street and the suburban forest. The control site was located in Uzyukovsky Bor (25 km from the city limits).

The object of the study was Betula Pendula Roth, which grows in all areas of the city and outside the city limits. This is a species of plants of the Birch genus (Betula), Birch family (Betulaceae). Fast growing tree species. It is very photophilous, its crown is openwork and lets in a lot of light.

The subject of the study is a quantitative indicator of the stomata of the leaf blade of Betula pendula Roth. This technique was tested for Betula pendula Roth, growing in various natural cenoses and urban areas of the city. Togliatti, Samara region.

An assessment of the anatomical and physiological state of leaf blades of the studied species was carried out in June, July and August using a method developed on the basis of standard methods. The study of anatomical and physiological parameters was carried out by counting the number of stomata per 1 mm2 using a microscope. Mathematical processing of the obtained data was carried out using the Microsoft Office package - Microsoft Excel. Correlation analysis was used to interpret the results obtained.

Middle-aged plants were used for analysis. Leaves were taken from the lower part of the crown, at the level of a raised hand, with maximum quantity available branches (from branches in different directions, conditionally - north, south, west, east) 10 leaves from each tree in each area. Leaves were taken of approximately the same size, average for this species.

Stomatal counts were carried out in laboratory conditions. On the evaporating surface of the leaf of the leaf blades prepared for the experiment, surface cuts were made every 2-3 mm with a scalpel at right angles to the central vein and a thin layer of the epidermis was cut off. The epidermis of the leaf blade was placed in a drop of water on a glass slide, covered with a coverslip and examined under a light microscope at low magnification, and then the microscope was switched to higher magnification with a x40 objective and x16 eyepiece. In this case, the microscrew was used to slightly change the focus in order to detect all the stomata in the area under consideration. The average number of stomata in the field of view of the microscope was determined by examining several (3-4) fields of view in different parts of the preparation. The number of stomata in a light spot was counted in three places on each leaf: two places were chosen on a mentally drawn straight line from the central vein to the edge of the leaf, and a third was chosen at the top of the leaf.

RESULTS AND DISCUSSIONS

The results of the study showed that Betula pendula Roth., growing within the city - Industrial zone, Victory Park and Banykin street, has a greater number of stomata per 1

mm of leaf surface, compared with suburban forest and control - Uzyukovsky pine forest. The maximum increase in the number of stomata per 1 mm2 of leaf blade is observed in the Industrial zone. When approaching highways, the number of stomata increases sharply. The obtained indicators of the number of stomata of leaf blades in 2014 were higher than in 2013. Due to the fact that 2014 was drier than 2013. The summer season of 2013 was characterized by frequent precipitation in the form of rain. Visual comparison of stomatal sizes from leaves from different points cities showed a visible decrease in their size as the air pollution increases.

The integrity of stomatal cells is disrupted under the influence of chemical air pollution. Stomatal guard cells are not able to regulate the width of the stomatal fissure. As a result, the stomata are constantly open and the plant’s water consumption for transpiration increases. What does the plant do in such a situation? Increases the number of stomata on its leaf blades, thereby compensating for the reduction in leaf size. A decrease in the area of ​​leaf blades irreversibly leads to a reduction in the stomatal apparatus, therefore an increase in the number of stomata with a decrease total area leaves leads to the preservation of the functions of gas exchange and transpiration of the leaf blades of Betula pendula Roth. The data obtained over two years of research indicate that the decrease in the size of leaf blades is compensated by an increase in the number of stomata. Compared to reference area 202

Terrestrial ecosystems

in the Industrial Zone 445 (an increase of 2.2 times was noted), in Victory Park 411 (an increase of 2 times), on Banykin Street 334 (by 1.6 times) and in the suburban forest 244 (by 1.2 times). From the diagram

it can be seen that over the year the number of stomata of leaf blades increased by an average of 3.5 times.

500.00 а ■о g 450.00 i S з с S ï 400.00 II g 1 350.00 § О ÜJ ^ 300.00 iä s E 250.00 i i ¥ 4 200.00 3 4 * 150.00 461.00 4Ï!),00 --■

206, OO^^^i-^^^231.00

Uzyunovsky Forest Urban Forest Banykin Street Victory Park Industrial Zone

Number of stomata per 1mm2 (2013) 198.00 231.00 319.00 392.00 429.00

Number of stomata per 1mm2 (2014) 206.00 257.00 348.00 430.00 461.00

Rice. Results of estimation of the number of stomata of the Betula pendula Roth leaf. for 2013-2014 CONCLUSION

Based on the calculations it was calculated

average number of stomata per 1 mm of leaf blade. Prototypes were collected from various sites. Based on the results, a graph was constructed in which the average data from different points of the study were expressed in a curved line, indicating an increase in the number of stomata as air pollution increased. The experimental data we obtained indicate that in the city. Togliatti, in conditions of complex atmospheric air pollution, increased content of vehicle exhaust gases, a weakening of the vital state of Betula pendula Roth is observed, which is expressed in a deterioration in the anatomical and physiological characteristics of the leaves. However, an increase in the number of stomata on the leaf blade, changes in the area and mass of the leaf, dispersion, and leaf anatomy should be considered as an adaptation of the Betula pendula Roth population to the conditions of technogenic pollution of the urban environment.

Betula pendula Roth, a highly adaptable species. But the anthropogenic load, growing every year, is so great that there are more dead individuals than adapted ones. It is clear that to improve the environmental situation in Togliatti, it is necessary to plant Betula pendula Roth in places where there is no vegetation and there are roads with heavy traffic (for example, an Industrial zone). Preserving individuals of Betula pendula Roth is as necessary as planting young specimens, because the death of one plant species means a threat to the existence of 10 to 30 species of living beings.

Ecological and biological assessment of the state of woody plants according to various bioindicative indicators should be used when using

following the state of the plant and the urban environment.

ACKNOWLEDGMENTS

The author expresses deep gratitude and sincere gratitude to his scientific supervisor C.B. Saksonov (IEVB RAS, Togliatti) for understanding, support and valuable advice, V.N. Kozlovsky (PVGUS, Tolyatti) for guiding him on the true path and invaluable support, O.V. Kozlovskaya (PVGUS, Togliatti) for personal example and invaluable support, A.B. Grebenkin (Russian State University for the Humanities, Tolyatti-Moscow) and A.S. Mych-kina (VEGU, Tolyatti) for assistance in field collection of material and friendly support, M.A. Pyanov for constructive criticism (PVGUS, Tolyatti), V.M. Vasyukov (IEVB RAS, Togliatti) and A.B. Ivanova (IEVB RAS, Tolyatti) for valuable advice and kind attitude. Special thanks for my understanding and patience to my dear mother L.V. Belyaeva.

BIBLIOGRAPHY

1. Alekseev V.A. Forest ecosystems and atmospheric pollution. L.: Science. 1990. 197 p.

2. Belyaeva Yu.V. Results of a study of the water-holding capacity of leaf blades of Betula pendula roth., growing under conditions of anthropogenic influence (using the example of Togliatti) // News of the Samara Scientific Center of the Russian Academy of Sciences. 2014. T. 16, No. 5 (5). S. 16541659.

3. Bioecological research [Internet resource] - Access mode: http://nsmelaya.narod.ru/ecopraktika.htm

4. Bulygin N.E., Yarmishko V.T. Dendrology: textbook / 2nd ed. erased - M.: MGUL, 2003. 528 p.

5. Grozdova N.B., Nekrasov V.I., Globa-Mikhailenko D.A. Trees, shrubs and vines. M: Timber Industry, 1986.

6. Zakharov V.M., Baranov A.S., Borisov V.I. and others. Environmental health: assessment methods. M.: Center for Environmental Policy of Russia, 2000. 68 p.

7. Kavelenova L.M. Problems of organizing a phytomonitoring system for the urban environment in forest-steppe conditions. Samara: Univers Group Publishing House, 2006. 223 p.

8. Kavelenova L.M. Ecological foundations and principles of constructing a system of phytomonitoring of the urban environment in the forest-steppe // Vestnik Sam. state University, 2003, special. issue 2. 182-191.

9. Kavelenova L.M., Prokhorova N.V. Plants in bioindication environment. Tutorial. Samara, 2012.

10. Kozlovskaya O.V. Materials for the flora of the village of Povolzhsky and its environs (Togliatti urban district). 1: Dicotyledonous plants // Ecology and geography of plants and communities of the Middle Volga region. Materials of the III scientific conference (Tolyatti, IEVB RAS, October 3-5, 2014) / Ed. S.A. Senator, C.B. Saxonova, G.S. Rosenberg. Tolyatti: Kassandra, 2014. pp. 210-216.

11. Kulagin Yu.Z. Woody plants and the industrial environment. M.: Nauka, 1974. 125 p.

12. Nikolaevsky B.S. Biological basis of gas resistance of plants. Novosibirsk: Nauka, 1979. 280 p.

13. Polevoy V.V. Physiology of plants. M. 1989. 464 p.

14. Saeenko O.V., Saxony S.B., Senator S.A. Materials for the flora of the Uzyukovsky forest // Research in the field of natural sciences and education. Interuniversity. Sat. scientific research works Vol. 2. Samara, 2011. pp. 48-53.

15. Saxony S.B., Senator S.A. Guide to Samara flora (1851-2011). Flora of the Volga basin. T.I. Tolyatti: Kassandra, 2012. 511 p.

16. Tolyatti Specialized Hydrometeorological Observatory of a state institution, Samara Center for Hydrometeorology and Environmental Monitoring (data).

RESULTS QUANTITY OF STOMA LAMINA BETULA PENDULA ROTH., GROWING UNDER ANTHROPOGENIC IMPACT (ILLUSTRATED G.O.TOLYATTI)

© 2015 Y. Belyaeva

Institute of ecology of Volga basin of RAS, Togliatti

This research work is devoted to the study of the water regime Betula pendula Roth. The evaluation was conducted according to a study of quantitative indicators of stomata of the leaf blades. Analyzing was conducted in the summer. It was found that in the early summer high performance water-holding capacity, and at the end of the summer, closer to the fall - low. These data show a strong dependence of the number of stomata on air pollution habitats studied species.

Key words: water regime, quantitative indicators of stomata, leaf blades, Betula pendula Roth., developmental stability, anthropogenic, biotic and abiotic factors.

Belyaeva Julia Vitaljevna, assistant, [email protected]

Option 1.

Exercise 1.

What concept should be entered in the blank in this table? 1) corolla 2) pistil 3) stamen 4) ovary

Task 2. P (2)

Xat

How many seeds out of the total number will germinate on the 7th day?

10% 2) 12% 3) 15% 4) 17%

Task 3

Determine the correct designation of the types of roots.

1 - adventitious root, 2 - lateral root, 3 - main root

1 - main root, 2 - adventitious root, 3 - lateral root

1 - main root, 2 - lateral root, 3 - adventitious root

1− lateral root, 2 — adventitious root, 3 — main root

Task 4

Table

4) Draw the stomata and label the main parts of the stomata in the drawing.

Task 5.

Establish the sequence of layers in the stem of a woody plant, starting from its surface. Write down the corresponding sequence of numbers in your answer.

1) bast

2) cork

3) wood

4) cambium

5) core

Task 6

_____________________________________________________________________

A flower is a modified shoot adapted for sexual reproduction. Its function is the formation of fruits and seeds. That is why the flower is also called the organ of seed reproduction.

In order to fulfill its main function, the flower has a specific structure. It consists of a peduncle, receptacle, flower leaves (sepals and petals), stamens and pistils.

The peduncle is the part of the stem on which the remaining parts of the flower are located. With the help of the peduncle, the flower is supplied nutrients and growing. The receptacle is located on the upper expanded part of the peduncle. Flower leaves are attached to it, which are arranged in rings (circles). The first ring is usually formed by green sepals, which in some flowers are free, while in others they are fused. Together they form the calyx of the flower. It performs a protective function. There is a corolla located above the cup. It usually consists of colored petals that serve to protect the stamens, pistils and to attract
animals - plant pollinators. The color of the petals depends on the chromoplasts or the pigments of the cell sap. The perianth is formed from the calyx and corolla.

The stamens are located inside the perianth behind the petals. Each stamen consists of an anther and a filament. The filament holds the anther, which consists of pollen sacs in which pollen develops.

At the very center of the flower is the pistil(s). The pistil consists of an ovary, a style and a stigma. The ovary contains ovules, from which the seed develops after pollination and fertilization. A column on which the stigma is located extends from the ovary. The stigma is the upper part of the pistil where the pollen grain enters and germinates. The stigma secretes a sticky liquid to trap pollen grains.

Task 7. P (5) Characterize the plant based on its morphological characteristics.

Stem:

A) erect;

B) creeping

Root system:

A) rod;

B) fibrous

Leaf venation

A) mesh;

B) parallel;

B) arc.

Sheet:

A) petiolate

B) sedentary

Perianth

A) simple;

B) double.

Independent work on the topic: “Plant organs”

Option 2.

Exercise 1.

In the table below, there is a relationship between the positions in the first and second columns.

What concept should be entered in the blank in this table?

Receptacle; 2) pestle; 3) stamen; 4) ovary.

Task 2. P (2)

Study the graph of the dependence of the number of sprouted seeds of a certain mass (3-4 mg) on ​​the duration of the seeds being in the soil (along the axisXtime is plotted (in days), and the axisat- the number of sprouted seeds from their total number (in%)).

How many seeds out of the total number will germinate on the 11th day?

10% 2) 12% 3) 15% 4) 17%

Task 3

Establish the correct sequence of layers in the stem of a woody plant, starting from the surface.

Heartwood - bark - wood - cambium;

Bark - cambium - wood - pith;

Bark - wood - cambium - pith;

Wood - cambium - bark - pith.

Task 4 Using the table “The number of stomata in some plants,” answer the following questions.

Table

The number of stomata in some plants

1) What function do leaf stomata perform?

2) How are the stomata located in most of the plants presented in the table?

3) Explain why oak and apple trees have stomata on the underside of their leaves.

4) sketch the stomata and indicate the main parts of the stomata in the drawing.

Task 5.

Establish the sequence of root zones, starting with the root cap.

1) Root cap

2) suction zone

3) division zone

4) venue area

5) stretching (growth) zone

Task 6 Read the text. Complete the tasks given below in the text.

______________________________________________________________________

After pollen ripens, the pollen grain is transferred to the stigma. This process is called pollination.

In some plants, ripe pollen lands on the stigma of the same flower, leading to self-pollination. However, in most plants, pollen from one flower is transferred to the stigma of another flower with the help of wind, water, animals, and humans. This type of pollination is called cross pollination. The most common in nature is cross-pollination with the help of animals (insects). To attract insects, special glands develop in the flower - nectaries, which secrete a sugary liquid (nectar). Flying from flower to flower and feeding on nectar, insects pollinate flowering plants, carrying pollen on its paws.

In many woody, steppe and meadow plants, cross-pollination is carried out with the help of the wind. These plants are wind pollinated. In their flowers, the stigma of the pistil is usually long and branched, and the stamens have long thin filaments that easily unwind when the wind blows.

The flowers of insect-pollinated plants are large and brightly colored. If the flowers are bright but small, then they are collected in inflorescences.

Wind-pollinated plants bloom in the spring before the leaves emerge.

Exercise:

Title the text

Fill the table. If the named characteristic is characteristic of a given group of plants, a “+” sign is placed, if not, then a “-”.

Characteristics of wind-pollinated and insect-pollinated plants.

Give an answer to the question.

Why, when clover seeds were brought to Australia and sown, the clover bloomed well, but there were no fruits or seeds?

Task 7. Characterize the plant based on its morphological characteristics.

Stem:

A) erect;

B) creeping

Root system:

A) rod;

B) fibrous

Leaf venation

A) mesh;

B) parallel;

B) arc.

Sheet:

A) petiolate

B) sedentary

Inflorescence

A) brush;

B) basket;

B) head;

Task 4.

Answer form for independent work

Who published this discovery in 1675 in his work Anatome plantarum. However, he did not understand their real function. At the same time, his contemporary Nehemiah Grew developed a hypothesis about the participation of stomata in the ventilation of the internal environment of a plant and compared them with the trachea of ​​insects. Progress in the study came in the 19th century, and then, in 1827, the Swiss botanist Decandolle first used the word “stoma”. The study of stomata at that time was carried out by Hugo von Mohl, who discovered the basic principle of opening stomata, and Simon Schwendener, who classified stomata according to the type of their structure.

Some aspects of the functioning of stomata continue to be intensively studied at the present time; The material is mainly Commelina vulgaris ( Commelina communis), garden bean ( Vicia faba), sweet corn ( Zea mays).

Structure

The dimensions of the stomata (length) range from 0.01-0.06 mm (the stomata of polyploid plants and leaves growing in the shade are larger. The largest stomata were found in an extinct plant Zosterophyllum, 0.12 mm (120 µm) The pore consists of a pair of specialized cells called guard cells (cellulae claudentes), which regulate the degree of openness of the pore; between them there is a stomatal fissure (porus stomatalis). The walls of the guard cells are thickened unevenly: those directed towards the gap (abdominal) are thicker than the walls directed from the gap (dorsal). The gap can expand and contract, regulating transpiration and gas exchange. When there is little water, the guard cells adhere tightly to each other and the stomatal fissure is closed. When there is a lot of water in the guard cells, it puts pressure on the walls and thinner walls are stretched more, and thicker ones are pulled inward, a gap appears between the guard cells. Under the gap there is a substomatal (air) cavity, surrounded by cells of the leaf pulp, through which gas exchange directly occurs. Air containing carbon dioxide (carbon dioxide) and oxygen enters the leaf tissue through these pores and is further used in the process of photosynthesis and respiration. Excess oxygen produced during photosynthesis by the internal cells of the leaf is released back into the environment through these same pores. Also, during the evaporation process, water vapor is released through the pores. Epidermal cells adjacent to the trailing ones are called accompanying cells (collateral, neighboring, parastomatal). They are involved in the movement of guard cells. The guard and accompanying cells form the stomatal complex (stomatal apparatus). The presence or absence of stomata (the visible parts of stomata are called stomatal lines) are often used in classifying plants.

Types of stomata

The number of accompanying cells and their location relative to the stomatal fissure make it possible to distinguish a number of types of stomata:

• anomocytic - accompanying cells do not differ from other cells of the epidermis, the type is very common for all groups of higher plants, with the exception of conifers;
• diacite - characterized by only two accompanying cells, the common wall of which is at right angles to the guard cells;
• paracytic - accompanying cells are located parallel to the guard cells and stomatal fissure;
• anisocytic - guard cells are surrounded by three accompanying cells, one of which is noticeably larger or smaller than the others, this type is found only in flowering plants;
• tetracytic - four accompanying cells, characteristic of monocots;
• encyclocytic - accompanying cells form a narrow wheel around the guard cells;
• actinocyte - several accompanying cells radiating from the guard cells;
• pericytic - guard cells are surrounded by one secondary accompanying cell, the stomata is not connected to the accompanying cell by an anticlinal cell wall;
• desmocyte - guard cells are surrounded by one accompanying cell, the stomata is connected to it by an anticlinal cell wall;
• polocytic - guard cells are not completely surrounded by one accompanying one: one or two epidermal cells adjoin one of the stomatal poles; the stomata is attached to the distal side of a single accompanying cell, having a U- or horseshoe shape;
• stephanocytic - stomata surrounded by four or more (usually five to seven) poorly differentiated accompanying cells, forming a more or less distinct rosette;
• laterocytic - this type of stomatal apparatus is considered by most botanists as a simple modification of the anomocytic type.

In dicotyledons, the paracytic type of stomata is common. The kidney-shaped (bean-shaped) guard cells - as they are visible from the surface of the leaf - carry chloroplasts; thin, non-thickened sections of the shell form protrusions (spouts) covering the stomatal fissure.

The outer walls of the guard cells usually have projections, which are clearly visible in the cross section of the stomata. The space enclosed by these outgrowths is called the front yard. Often similar growths are observed in the inner membranes of guard cells. They form a back yard, or inner courtyard, connected to a large intercellular space - the substomatal cavity.

In monocots, the paracytic structure of stomata is noted in cereals. The guard cells are dumbbell-shaped - narrowed in the middle part and expanded at both ends, while the walls of the expanded areas are very thin, and in the middle part of the guard cells they are very thick. Chloroplasts are located in the vesicle-shaped ends of cells.

Movement of guard cells

The mechanism of movement of guard cells is very complex and varies among different types. In most plants, with unequal water supply at night, and sometimes during the day, the turgor in the guard cells decreases and the stomatal gap closes, thereby reducing the level of transpiration. With an increase in turgor, the stomata open. It is believed that the main role in changing turgor belongs to potassium ions. The presence of chloroplasts in guard cells is essential in the regulation of turgor. The primary starch of chloroplasts, turning into sugar, increases the concentration of cell sap. This promotes the influx of water from neighboring cells and increases turgor pressure in the guard cells.

Stomatal location

Dicotyledonous plants, as a rule, have more stomata in the lower part of the leaf than in the upper part. This is explained by the fact that the upper part of a horizontally located leaf, as a rule, is better illuminated, and a smaller number of stomata in it prevents excessive evaporation of water. Leaves with stomata located on the underside are called hypostomatic.

In monocotyledonous plants, the presence of stomata in the upper and lower parts of the leaf is different. Very often the leaves of monocots are arranged vertically, in which case the number of stomata on both parts of the leaf may be the same. Such leaves are called amphistomatic.

Floating leaves do not have stomata on the lower part of the leaf so that they can absorb water through the cuticle. Leaves with stomata located on the upper side are called epistomatic. Underwater leaves have no stomata at all.

The stomata of coniferous plants are usually hidden deep under the endodermis, which makes it possible to greatly reduce water consumption for evaporation in winter, and during drought in summer.

Mosses (with the exception of Anthocerotes) lack true stomata.

Stomata also differ in their level of location relative to the surface of the epidermis. Some of them are located flush with other epidermal cells, others are raised above or buried below the surface. In monocots, whose leaves grow predominantly in length, the stomata form regular parallel rows, while in dicotyledons they are arranged randomly.

Carbon dioxide

Since carbon dioxide is one of the key reagents in the process of photosynthesis, most plants have stomata open during the day. The problem is that when air enters, it mixes with water vapor evaporating from the leaf, and therefore the plant cannot gain carbon dioxide without simultaneously losing some water. Many plants have protection against water evaporation in the form of wax deposits that clog the stomata.

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Notes

Literature

• // Encyclopedic Dictionary of Brockhaus and Efron: in 86 volumes (82 volumes and 4 additional). - St. Petersburg. , 1890-1907.
• Atlas of plant anatomy: textbook. manual for universities / Bavtuto G. A., Eremin V. M., Zhigar M. P. - Mn. : Urajai, 2001. - 146 p. - (Textbook and teaching aids for universities). - ISBN 985-04-0317-9.
• Colin Michael Willmer, Mark Fricker. Stomata. - Chapman & Hall, 1995. - ISBN 0412574306.

Footnotes

Excerpt characterizing Ustice

Suddenly everything began to move, the crowd began to speak, moved, moved apart again, and between the two parted rows, at the sound of music playing, the sovereign entered. The master and hostess followed him. The Emperor walked quickly, bowing to the right and left, as if trying to quickly get rid of this first minute of the meeting. The musicians played Polskoy, known then by the words composed on it. These words began: “Alexander, Elizabeth, you delight us...” The Emperor walked into the living room, the crowd poured to the doors; Several faces with changed expressions hurriedly walked back and forth. The crowd again fled from the doors of the living room, in which the sovereign appeared, talking with the hostess. Some young man with a confused look stepped on the ladies, asking them to move aside. Some ladies with faces expressing complete obliviousness to all conditions of the world, spoiling their toilets, pressed forward. The men began to approach the ladies and form Polish pairs.
Everything parted, and the sovereign, smiling and leading the mistress of the house by the hand, walked out of the living room door. Behind him came the owner with M.A. Naryshkina, then envoys, ministers, various generals, whom Peronskaya kept calling. More than half of the ladies had gentlemen and were going or preparing to go to Polskaya. Natasha felt that she remained with her mother and Sonya among the minority of ladies who were pushed to the wall and not taken in Polskaya. She stood with her thin arms hanging down, and with her slightly defined chest rising steadily, holding her breath, her shining, frightened eyes looked ahead of her, with an expression of readiness for the greatest joy and the greatest sorrow. She was not interested in either the sovereign or all the important persons to whom Peronskaya pointed out - she had one thought: “is it really possible that no one will come up to me, will I really not dance among the first, will all these men who are now not notice me?” It seems that they don’t even see me, and if they look at me, they look with such an expression as if they were saying: Ah! it's not her, there's nothing to watch. No, this cannot be! - she thought. “They should know how much I want to dance, how great I am at dancing, and how much fun it will be for them to dance with me.”
The sounds of the Polish, which continued for quite a long time, were already beginning to sound sad - a memory in Natasha’s ears. She wanted to cry. Peronskaya moved away from them. The Count was at the other end of the hall, the Countess, Sonya and she stood alone as if in a forest in this alien crowd, uninteresting and unnecessary to anyone. Prince Andrey walked past them with some lady, obviously not recognizing them. Handsome Anatole, smiling, said something to the lady he was leading, and looked at Natasha’s face with the same look as one looks at the walls. Boris walked past them twice and turned away each time. Berg and his wife, who were not dancing, approached them.
Natasha found this family bonding here at the ball offensive, as if there was no other place for family conversations except at the ball. She did not listen or look at Vera, who was telling her something about her green dress.
Finally, the sovereign stopped next to his last lady (he was dancing with three), the music stopped; the preoccupied adjutant ran towards the Rostovs, asking them to step aside somewhere else, although they were standing against the wall, and the distinct, cautious and fascinatingly measured sounds of a waltz were heard from the choir. The Emperor looked at the audience with a smile. A minute passed and no one had started yet. The adjutant manager approached Countess Bezukhova and invited her. She raised her hand, smiling, and placed it, without looking at him, on the adjutant’s shoulder. The adjutant manager, a master of his craft, confidently, slowly and measuredly, hugging his lady tightly, set off with her first on a glide path, along the edge of the circle, at the corner of the hall, he picked up her left hand, turned it, and because of the ever-accelerating sounds of the music, only measured ones were heard the clicks of the spurs of the adjutant’s quick and dexterous legs, and every three beats at the turn, his lady’s fluttering velvet dress seemed to flare up. Natasha looked at them and was ready to cry that it was not she who was dancing this first round of the waltz.
Prince Andrei, in his colonel's white (cavalry) uniform, in stockings and shoes, lively and cheerful, stood in the front rows of the circle, not far from the Rostovs. Baron Firgof spoke with him about tomorrow's supposed first meeting state council. Prince Andrei, as a person close to Speransky and participating in the work of the legislative commission, could give correct information about the meeting tomorrow, about which there were various rumors. But he did not listen to what Firgof told him, and looked first at the sovereign, then at the gentlemen who were getting ready to dance, who did not dare to join the circle.
Prince Andrei observed these gentlemen and ladies timid in the presence of the sovereign, dying with desire to be invited.
Pierre walked up to Prince Andrei and grabbed his hand.
– You always dance. There is my protegee [favorite], young Rostova, invite her,” he said.
- Where? – asked Bolkonsky. “Sorry,” he said, turning to the baron, “we’ll finish this conversation somewhere else, but we have to dance at the ball.” “He stepped forward in the direction that Pierre pointed out to him. Natasha’s desperate, frozen face caught the eye of Prince Andrei. He recognized her, guessed her feeling, realized that she was a beginner, remembered her conversation at the window and with a cheerful expression on his face approached Countess Rostova.
“Let me introduce you to my daughter,” said the countess, blushing.
“I have the pleasure of being an acquaintance, if the countess remembers me,” said Prince Andrei with a polite and low bow, completely contradicting Peronskaya’s remarks about his rudeness, approaching Natasha and raising his hand to hug her waist even before he finished the invitation to dance. He suggested a waltz tour. That frozen expression on Natasha’s face, ready for despair and delight, suddenly lit up with a happy, grateful, childish smile.
“I’ve been waiting for you for a long time,” as if this frightened and happy girl said, with her smile that appeared behind the ready tears, raising her hand on Prince Andrei’s shoulder. They were the second couple to enter the circle. Prince Andrey was one of the best dancers of his time. Natasha danced superbly. Her feet in ballroom satin shoes quickly, easily and independently of her did their job, and her face shone with the delight of happiness. Her bare neck and arms were thin and ugly. Compared to Helen's shoulders, her shoulders were thin, her breasts were vague, her arms were thin; but Helen already seemed to have a varnish on from all the thousands of glances sliding over her body, and Natasha seemed like a girl who had been exposed for the first time, and who would have been very ashamed of it if she had not been assured that it was so necessary.
Prince Andrei loved to dance, and wanting to quickly get rid of the political and intelligent conversations with which everyone turned to him, and wanting to quickly break this annoying circle of embarrassment formed by the presence of the sovereign, he went to dance and chose Natasha, because Pierre pointed him out to her and because she was the first of the pretty women to come into his sight; but as soon as he embraced this thin, mobile figure, and she moved so close to him and smiled so close to him, the wine of her charm went to his head: he felt revived and rejuvenated when, catching his breath and leaving her, he stopped and began to look on the dancers.

Stomata in a plant are pores located in the layers of the epidermis. They serve for evaporation excess water and gas exchange of the flower with the environment.

They first became known in 1675, when naturalist Marcello Malpighi published his discovery in Anatome plantarum. However, he was unable to unravel their real purpose, which served as an impetus for the development of further hypotheses and research.

History of the study

The 19th century saw long-awaited progress in research. Thanks to Hugo von Mohl and Simon Schwendener, the basic principle of the operation of stomata and their classification according to the type of structure became known.

These discoveries gave a powerful impetus to the understanding of the functioning of pores, but some aspects of previous research continue to be studied to this day.

Leaf structure

Plant parts such as the epidermis and stomata are classified as internal structure leaf, but first you should study its external structure. So, the sheet consists of:

• Leaf blade - a flat and flexible part responsible for photosynthesis, gas exchange, water evaporation and vegetative propagation (for certain species).
• The base in which the growth plate and petiole are located. It also helps attach the leaf to the stem.
• Stipules are paired formations at the base that protect the axillary buds.
• Petiole - the tapering part of the leaf that connects the blade to the stem. It is responsible for vital functions: orientation towards light and growth through educational tissue.

The external structure of the leaf may vary slightly depending on its shape and type (simple/complex), but all of the above parts are always present.

The internal structure includes the epidermis and stomata, as well as various formative tissues and veins. Each of the elements has its own design.

For example, the outer side of a leaf consists of living cells that differ in size and shape. The most superficial of them are transparent, allowing sunlight to penetrate into the leaf.

Smaller cells located somewhat deeper contain chloroplasts, which give leaves green color. Due to their properties, they were called closing. Depending on the degree of moisture, they either shrink or form stomatal slits between themselves.

Structure

The length of a plant's stomata varies depending on the type and degree of light it receives. The largest pores can reach 1 cm in size. The stomata form guard cells that regulate the level of its opening.

The mechanism of their movement is quite complex and varies for different plant species. In most of them - depending on the water supply and the level of chloroplasts - the turgor of cell tissues can either decrease or increase, thereby regulating the opening of the stomata.

Purpose of the stomatal fissure

There is probably no need to dwell in detail on such an aspect as the functions of the sheet. Even a schoolchild knows about this. But what are stomata responsible for? Their task is to ensure transpiration (the process of water movement through a plant and its evaporation through external organs such as leaves, stems and flowers), which is achieved through the work of guard cells. This mechanism protects the plant from drying out in hot weather and does not allow the process of rotting to begin in conditions of excessive humidity. The principle of its operation is extremely simple: if the amount of fluid in the cells is not high enough, the pressure on the walls drops and the stomatal fissure closes, maintaining the moisture content required to maintain life.

And on the contrary, its excess leads to increased pressure and the opening of pores through which excess moisture evaporates. Due to this, the role of stomata in cooling plants is also great, since the air temperature around it decreases precisely through transpiration.

Also under the gap there is an air cavity that serves for gas exchange. Air enters the plant through the pores to subsequently enter into respiration. Excess oxygen then escapes into the atmosphere through the same stomatal gap. Moreover, its presence or absence is often used to classify plants.

Worksheet Functions

The leaf is an external organ through which photosynthesis, respiration, transpiration, guttation and vegetative propagation are carried out. Moreover, it is able to accumulate moisture and organic matter through stomata, and also provide the plant with greater adaptability to difficult environmental conditions.

Since water is the main intracellular medium, the excretion and circulation of fluid inside a tree or flower are equally important for its life. In this case, the plant absorbs only 0.2% of all moisture passing through it, the rest goes to transpiration and guttation, due to which the movement of dissolved mineral salts and cooling occurs.

Vegetative propagation often occurs by cutting and rooting flower leaves. Many houseplants grown in this way, because this is the only way to preserve the purity of the variety.

As mentioned earlier, they help adapt to various natural conditions. For example, transformation into spines helps desert plants reduce moisture evaporation, tendrils enhance the functions of the stem, and large sizes often serve to preserve liquid and nutrients where climatic conditions do not allow replenishing reserves regularly.

And this list can be continued endlessly. At the same time, it is difficult not to notice that these functions are the same for the leaves of flowers and trees.

What plants do not have stomata?

Since the stomatal fissure is characteristic of higher plants, it is present in all species, and it is a mistake to consider it absent, even if a tree or flower has no leaves. The only exception to the rule is kelp and other algae.

The structure of stomata and their work in conifers, ferns, horsetails, and swimmers differ from those in flowering plants. In most of them, during the day the slits are open and actively participate in gas exchange and transpiration; The exception is cacti and succulents, whose pores open at night and close in the morning to conserve moisture in arid regions.

Stomata in a plant whose leaves float on the surface of the water are located only in the upper layer of the epidermis, and in “sessile” leaves - in the lower layer. In other varieties, these slots are present on both sides of the plate.

Stomata location

The stomatal slits are located on both sides of the leaf blade, but their number in the lower part is slightly greater than in the upper part. This difference is due to the need to reduce moisture evaporation from a well-lit sheet surface.

For monocotyledonous plants, there is no specificity regarding the location of stomata, since it depends on the direction of growth of the plates. For example, the epidermis of vertically oriented plant leaves contains the same number of pores in both the upper and lower layers.

As mentioned earlier, floating leaves do not have stomatal slits on the underside, since they absorb moisture through the cuticle, like completely aquatic plants, which do not have such pores at all.

Stomata coniferous trees are located deep under the endodermis, which contributes to a decrease in the ability to transpirate.

Also, the location of the pores differs relative to the surface of the epidermis. The slits can be level with the rest of the “skin” cells, go higher or lower, form regular rows, or be scattered randomly across the integumentary tissue.

In cacti, succulents and other plants whose leaves are missing or have changed, transforming into needles, stomata are located on the stems and fleshy parts.

Types

Stomata in a plant are divided into many types depending on the location of the accompanying cells:

• Anomocytic - considered as the most common, where by-products do not differ from others found in the epidermis. Like one of his simple modifications can be called laterocyte type.
• Paracytic - characterized by parallel abutment of accompanying cells relative to the stomatal fissure.
• Diacitic - has only two side particles.
• Anisocytic - a type found only in flowering plants, with three accompanying cells, one of which is noticeably different in size.
• Tetracytic - characteristic of monocots, has four accompanying cells.
• Encyclocytic - in it the side particles close in a ring around the closing ones.
• Pericytic - it is characterized by a stomata that is not connected to the accompanying cell.
• Desmocyte - differs from the previous type only in the presence of adhesion between the gap and the side particle.

Only the most popular types are listed here.

The influence of environmental factors on the external structure of the leaf

For the survival of a plant, its degree of adaptability is extremely important. For example, humid areas are characterized by large leaf blades and a large number of stomata, while in arid regions this mechanism operates differently. Neither flowers nor trees differ in size, and the number of pores is noticeably reduced to prevent excess evaporation.

Thus, it is possible to trace how parts of plants change over time under the influence of the environment, which also affects the number of stomata.