Which fully loaded in water . The growth and development of these plants occurs due to nutrients dissolved in water.
They obtain the oxygen necessary for breathing from water, as well as carbon dioxide, necessary for the creation of organic substances.
Oxygen and nutrients enter the plant through the thin walls of their outer cells. Such plants include:
To the most numerous representatives submerged plants include pondweeds. They are capable of diving into water depths of 3 m or more. It is also characteristic of them that the tissues of their stems contain a large amount of air. Using its lifting force, rising to the top, these plants can maintain their vertical position.
As the plants grow, they form fairly extensive underwater meadows. Their dense thickets serve as reliable shelter, highly nutritious food and a spawning site for many, including valuable species of fish.
Rdest perfoliate
Family Rdestovs , distributed in Eastern and Western Siberia, Altai. This is the most common species of this family. Pondweed pierced-leaved – flowering, quite large , with a long stem standing vertically in the water.
The stem is attached to the bottom of the reservoir by a rhizome; the leaves are hard, thick, oval-heart-shaped, located alternately on the stem. The leaves do not have petioles, so the leaf blades are directly attached to the stem.
Flowers Rdesta pierced-leaved, inconspicuous, small, yellowish-greenish in color, collected in loose spike-shaped inflorescences. Only for the time of flowering these plants submerged in water They release inflorescences above the surface of the reservoir; after flowering ends, they are again immersed in the water, where the fruits ripen. Pondweed is propagated by seeds and cuttings of rhizomes.
Growing Rdest pierced-leaved in ponds with hard water containing large amounts of lime. Therefore, during the life of the plant, lime from the water settles on the outer surface of the leaves in the form of a thin film. Pondweed forms vast underwater meadows with high productivity.
The leaves, stems, seeds, and rhizomes of this plant are highly nutritious food for muskrats, mallards, red-headed ducks, coots, fish, and waterfowl. In crushed form it serves as food for poultry and for the production of fertilizers.
Elodea Canadian
Family Aquaticaceae, native to North America. Elodea Canadian is plant completely submerged in water , much smaller in size than Rdes t pierced-leaved.
It has long, thin stems that spread along the bottom of the reservoir. They lie freely, without taking root. The leaves are elongated, transparent, oblong, have no petioles, located 3-4 on the stem. They form quite numerous whorls. The surface of the leaves is covered with a dirty, thin coating of lime.
Elodea Canadian is a flowering plant, but very small flowers with whitish petals appear extremely rarely, in July-August. Propagated vegetatively by dividing stems. Growing quickly and strongly in natural bodies of water, it forms continuous thickets at the bottom, which is not desirable. Therefore, this plant is called water plague.
Rdest brilliant
Family Pondweed , distributed in the temperate zone of the entire Northern Hemisphere. This is a tall flowering plant, the height of which reaches 1.5 m. It has a highly branched stem, sometimes its leafy shoots completely penetrate rather thick layers of water in reservoirs.
On a branched stem there are large, translucent, shiny bright green leaves, slightly wavy along the edge. The length of the leaves is 8-20 cm, the width is 1-3 cm. The tops of unexpanded leaves, like sharp stakes, rise above the surface of reservoirs.
The flowers are small, collected in an inflorescence in the form of a spike, these are only during flowering plants submerged in water
bloom inflorescences on the water surface of the reservoir. The plant blooms in June-July; after flowering ends, the inflorescences sink under water, where the fruits ripen. The fruits are broadly obovate with a short, thick nose. The fruits ripen in August; multiplies Rdest
brilliant by seeds and vegetatively.
Shiny pondweed, like pierced-leaved pondweed, can grow in hard water containing lime. Therefore, on the outer surface of the leaves of the brilliant pondweed there is a thin film of protruding lime.
The depth at which this plant can grow is 2.5-3 m. It forms dense underwater meadows, which are characterized by high productivity, at a depth of 1.7-2 m. The leaves, stems, and seeds of this plant are valuable food for muskrats, water rats, waterfowl.
Dense thickets Rdesta brilliant are a spawning place for fish, and for their young - feeding pastures. This plant can be used as a good fertilizer.
Rdest comb
The pondweed family, distributed in temperate zones of the Northern Hemisphere. It is a perennial, rhizomatous, plant submerged in water. It has a straight, thin, thread-like stem, highly branched at the top, the length of which is 50-100 cm. The leaves are submerged, thin, narrow, dark green or brownish in color, 5-15 cm long, 3-5 mm wide.
The flowers are brownish or greenish in color, have several petals, collected in paniculate inflorescences, which rise above the surface of the reservoir during the flowering period.
Blooms in June-July. After flowering ends, the inflorescences descend into the water column, where the fruits ripen. At the end of August, obovate fruits with a short nose appear.
Comb pondweed reproduces vegetatively and by seeds. These plants submerged in water
They grow and develop well not only in fresh water, but also in slightly brackish water, in which many aquatic plants cannot grow. Very nutritious food for muskrats, waterfowl and fish, carp, are the plant nodules that form on its rhizome in the fall, and seeds.
Dense thickets of Pondweed serve as a grazing area for waterfowl, a refuge for many species of fish and a spawning ground.
Rdest curly
The pondweed family, distributed in temperate zones of the Northern Hemisphere. Curly pondweed has a tetrahedral, rather branched stem, the height of which is 30-90 cm. The leaves are submerged, finely serrated, translucent, wavy or curly along the edge.
The inflorescences are short, few-flowered, located on slightly curved peduncles, the length of which is 2-3 cm. The plant blooms in June-August. Fruits with an elongated, curved nose, about one and a half millimeters long, ripen at the end of August.
Reproduces Rdest curly vegetatively and by seeds. Only in the warm period of the year, curly pondweed is a good nutritious food for animals, since it grows in areas of reservoirs up to 0.9 m deep. In winter, it is excluded from their diet, since the thickets are subject to freezing and become an inaccessible delicacy.
Pemphigus ordinary
Family Bubble , distributed throughout Europe. This is a perennial, highly branched, rootless plant. The stems, which reach 1 m in length, are completely submerged in water. On thread-like, repeatedly pinnately dissected leaves up to 5 cm long, there are many pale green vesicles with a diameter of 2-5 mm.
Each vesicle has a mouth opening; along its edges there are long, branched hairs and several stiff bristles. On the outside of the mouth there are many glands that secrete a sticky substance and sugar. This serves as bait for larvae, small crustaceans, daphnia, small worms, ciliates and fish fry. The valve opens even with a light touch, and, having caught the victim, immediately closes.
The inner surface of the vesicle is covered with glandular hairs that secrete enzymes to digest prey. That's why Pemphigus has the rare characteristics of flowering plants being completely submerged in water, like a carnivorous plant.
The flowers of the plant are orange-yellow, two-lipped, collected in a loose, irregularly shaped raceme. During flowering, the plant throws a loose brush onto the water surface.
Reproduces Pemphigus ordinary vegetatively overwintering, spherical buds. It does not form dense thickets, so its feeding value is low. However, it is a favorite delicacy of ducks, in particular the red-headed duck. It is also used as a medicinal plant in medicine.
Hornwort immersed
Family Hornfolia , distributed on all continents except Antarctica. Perennial, very decorative, dark green submerged plant. It can grow at a depth of a reservoir of up to 9 m. It has whitish, branched stems in the upper part, the length of which is 30-100 cm. Despite the fact that the plant is very sensitive to bright sun (that is, it dies in bright sunlight), the tops of its stems directed towards the sun.
On the stem there are finely dissected, that is, divided into numerous, rather narrow lobes, dark green leaves, 4-12 in whorls. The leaves are 1.5-2 cm long, serrated along one edge, and cartilaginous at the apex. In their shape and rigidity, the leaves resemble horns. Roots data plants completely submerged in water
do not have: their role is played by the green parts of the plant - the stem and dissected leaves. The plant absorbs nutrients and oxygen for respiration through the stem and leaves.
Flowers Hornwort submerged small, barely noticeable, without petals, unisexual, located one at a time in the leaf axils. The fruit is a nut, oval in shape, 4-5 mm long, has three spines: the apical one and two at the base of the fruit. Reproduces vegetatively; Before the onset of winter, the growth buds on the stem are covered with closely spaced whorls of leaves.
Hornwort submerged is a good nutritious food for waterfowl and fish.
Seed propagation
The seeds are propagated by pierced pondweed, brilliant pondweed, combed pondweed, and curly pondweed. The fruits of these plants, which are under water, in late August-early September, are collected while in a boat, picking them off with a hook.
The collected fruits are placed on the bottom of the boat, covered with damp moss, protecting them from drying out. The fruits are then placed in baskets or boxes with holes and dipped into water to fully ripen. After 7-12 days, the seeds, completely freed from fruit shells and mucus, are ready for sowing.
For sowing, the seeds are rolled into lumps of clay and lowered into clayey soil containing sand to a depth of 1.5 m. In the spring of next year, extensive underwater thickets of these plants are observed.
Vegetative propagation plants completely submerged in water
Pierced pondweed, Shiny pondweed, Curly pondweed propagated by division of rhizomes. In the spring, the rhizomes of these plants are hooked from the bottom of reservoirs from a boat with a hook and removed to the surface. The rhizomes are cut with a knife into cuttings 20-25 cm long. Each cutting must contain renewal buds (“eyes”). Having tied a load (gravel, crushed stone, pieces of brick) to the cuttings, they are lowered to the bottom of the reservoirs. The optimal time for cutting rhizomes and planting them is spring and summer. The following year, these plants produce extensive, dense underwater thickets.
Rdest comb– in autumn, numerous nodules form on the rhizome of the plant, which overwinter together with it at the bottom of the reservoir. In the spring, having separated the nodules containing renewal buds from the rhizome, they are planted to a depth of 1.5-1.8 m. The next year, in the spring, abundant thickets of this plant with a large number of seeds appear.
Elodea Canadian– this plant reproduces amazingly quickly vegetatively, that is, by dividing the stems. If a section of the stem of these immersed plants is placed in a vessel with water and placed in a well-lit, warm place, then in a few weeks a long shoot with many leaves will appear.
Pemphigus ordinary– reproduces by overwintering buds. These buds - turions - are formed at the end of summer, separate from the mother’s body, go under water, where they overwinter. Germinating in the spring, they give rise to new plants. Hornwort submerged reproduces by segments of stems containing growth buds.
The film manual contains a methodological apparatus that provides assistance to the teacher at all stages of the lessons.
Relevance:
Each species requires a certain amount of water. Swamp plants cannot grow in forests or dry steppes, and steppe and forest herbs cannot grow in waterlogged swamp soil.
Type of training session; studying and primary consolidation of new knowledge
Didactic purpose; create conditions for awareness and comprehension of a block of new educational information.
Forms of conducting classes; lecture, educational film
Basic Concepts
Coastal vegetation. Floating plants. Plants completely submerged in water. Aquatic plants with floating leaves
Issues for discussion
1.Why do duckweed plants float on water and not drown?
2.Why are the leaves of aquatic plants heavily dissected?
3.Why do aquatic plants dry out quickly without water?
4.What is the difference between floating and underwater water lily leaves?
5.How aquatic plants adapt to lack oxygen?
Each species requires a certain amount of water. Swamp plants cannot grow in forests or dry steppes, and steppe and forest herbs cannot grow in waterlogged swamp soil.
Based on how much water plants need and how they tolerate drought, they are grouped into different ecological groups. Let us consider these ecological groups and the adaptations of plants to life in different moisture conditions.
If we approach the shore of a lake or river, we will see a lushly grown coastal vegetation. There are plants in the water too. These are different algae that form the so-called ti-nu. But there are also many flowering plants. Let's take a closer look at some of them.
floating plants. Floats on the surface of the water duckweed Its shoot has turned into a small, 2-3 mm in size, green round plate. One root extends down from it. The plate of the common polyroot is slightly larger; not one, but several roots extend from it. The plates of duckweed and polyroot do not sink; they are light and buoyant, as they have air cavities. The roots help them maintain stability and not capsize during rough waters.
The plates branch, the lateral ones can separate, this is how vegetative propagation occurs. During the summer duckweed and polyroot often form a continuous cover on the surface of a small pond. They create shade and worsen lighting conditions for other aquatic plants. The plates overloaded with starch drown in the fall.
Plants completely submerged in water. Some of them have no roots and remain in the water column. This hornwort, common bladderwort. Others have roots and attach themselves to the bottom of the reservoir. These are Canadian elodea, water buttercups, and pondweeds.
In many plants, the leaves are dissected into very narrow, thread-like segments, for example, in water buttercups, uruti, hornwort, and bladderwort (Fig. 1). Such leaves use light more fully, and the penetration of water with carbon dioxide and mineral salts into them is facilitated. Plants submerged in water have very thin leaf blades. The light in the water is weak, so the leaves have a shadow structure without columnar tissue. Sometimes leaves consist of only two layers of cells ( Elodea canadensis). The skin has no stomata, and there is no cuticle on its surface.
Plants submerged in water absorb water and mineral salts over the entire surface of the body. Carbon dioxide and oxygen, dissolved in water, easily penetrate cells through thin membranes.
Fig.1. Dissected leaves of aquatic plants: 1 - submerged hornwort, 2 - rigid-leaved buttercup, 3 - spicate hornwort
If you take aquatic plants out of the water, their leaves will quickly dry out and become brittle, since they do not have a cuticle and they easily lose water.
Aquatic plants with floating leaves. This group includes common waterweed, floating pondweed, and yellow pod and different types of water lilies. The egg capsule has yellow flowers, and the water lilies have white flowers. Let's take a closer look at the yellow egg capsule (Fig. 2).
Only leaf blades of round or broad oval shape float on the surface of the water. They are brought to the surface by long, strong petioles that extend from a thick rhizome that takes root at the bottom of the reservoir. They also have underwater leaves, smaller and thinner, often rolled up and forming something like a cap. Floating leaves are well illuminated by the sun, they have a light structure, while underwater leaves have a shadow structure. The underside of the floating leaf is submerged in water. There are no stomata and no cuticle, so the leaf easily absorbs water. The skin on the upper side of the floating leaves has numerous stomata and cuticles.
Numerous roots extend from the rhizome. They secure plants at the bottom of the reservoir. But they do not have root hairs, like other aquatic plants. Starch accumulates in the rhizomes, which plants use in the spring to develop new shoots (Fig. 2).
Adaptations of aquatic plants to oxygen deficiency. Plants immersed in water use oxygen dissolved in water to breathe.
If some of the leaves of aquatic plants are in the air, then oxygen, along with the air, enters the plants through the stomata. In the leaf blades, petioles, stems, rhizomes and roots of such plants there are very large intercellular spaces, which are even called air chambers, or cavities. They communicate with each other, so air from the leaves can pass through them to the roots, which especially need oxygen, since they are immersed in muddy soil, saturated with water and containing no air. Air cavities can be seen even with the naked eye if you cut the petiole of a leaf of a water capsule or other aquatic plant. The leaves of aquatic plants floating on the water and protruding above the water evaporate a lot of water, since it is easily accessible to them
“Reproduction of algae” - Plan: The most progressive class. Order of the Charales. The genitals are on the leaf nodes. III. Order Zygnematales. II. 1. General characteristics of the class 2. Order Zignemaceae 3. Order Desmidiaceae 4. Order Characeae. Order Desmidiales.
“Algae Lesson” - Feedback. Can algae be unicellular or multicellular? 3. Working with “Black Box” concepts On the desk there is a sheet with a list of concepts. Raw materials for industry. Do algae have organs? Raw materials for the food industry. Does photosynthesis occur in algae cells in the light? Are algae autotrophs based on their feeding method?
“Plant and water” - On peat, or sphagnum, bogs - sphagnum mosses, sundew, cotton grass. Floating plants. Elodea. Pemphigus. Plants completely submerged in water. Each species requires a certain amount of water. What is the significance of water evaporation by plants? General adaptations of moisture-loving plants. Why do plants wither and what happens in the leaf cells?
“Aquatic plants” - Part II of the lesson – interactive. Task No. 2 Select material about seaweed. Ecological circle lesson form: interactive. "Virtual excursion with elements of research." Students' use of a computer program in botany. The teacher corrects the students' search activity as the task progresses.
“Plants in water” - Mesophytes. They usually live along the banks of water bodies and in damp meadows. Among xerophytes, a distinction is made between dry and succulent. Question 2: Which plant evaporates about 50 g of water per day? Cactus needles are dry and hard so as not to lose water. Question 1: Why does water flow from lily leaves? During the process of water exchange, the plant passes a lot of water through itself.
“Division of algae” - Sexual reproduction: Associated with the copulation of gametes and the formation of a zygote. As a result of division, four or eight daughter cells are formed. A mature sporophyte of kelp is a diploid plant with a length of 0.5 to 6 or more meters. What is the name of this algae? A diploid sporophyte develops from a zygote without a dormant period.
There are a total of 20 presentations in the topic
Most indoor plants can be propagated vegetatively - by cuttings, layering, children or dividing an adult plant. At first glance, everything is simple: cut off a cutting, stick it in the ground and wait for it to take root. In fact, such a trick is not always possible and not for everyone. This matter requires experience and skill.
For some people, everything they plant grows and prospers; in England they are called “green hands.” Most of us sometimes manage to root a cutting and grow a plant from it, but more often the planting material rots or dries out. What do you need to know about rooting cuttings in order to propagate your favorite indoor flowers without any problems?
What should be done
Before you begin harvesting cuttings and rooting them, it is important to decide on the following issues:
- Find out what kind of houseplant it is, whether it can be propagated by cuttings and read tips on how to do this specifically for this species;
- Select and cut the cuttings correctly;
- Prepare dishes for rooting and soil suitable for this plant;
- Treat with a root growth stimulator, if necessary;
- Plant the cuttings and care for them properly.
Some indoor plants take root easily and quickly. There are no problems with rooting, zonal,. Large-flowered pelargoniums are more capricious. Almost always successfully propagated by cuttings and. and difficult to root. If you don’t have any experience, then it’s better to practice on the most unpretentious and easily rooted house flowers.
How to cut cuttings correctly.
Rooting in water.
The easiest way to propagate houseplants is to cut a branch, put it in water and wait for the roots to appear. But not all plant species develop roots under such conditions. Many simply rot after a while. Impatiens, zonal pelargonium, tradescantia, and coleus are usually propagated in water.
What to root in? In any small glass or plastic container. In a glass, for example. It is noteworthy that roots appear faster in dark glass dishes. The cuttings are placed so that the lower part is submerged shallowly. Roots require the presence of oxygen to form; they form at the interface between water and air. The water level in the glass should be such that the ends of the cuttings are in the water, but most of them are above the water level.
What water should I use? Regular, from the tap. Some advise taking only boiled water, it does not contain microbes, but in fact they are introduced there as soon as the cutting is placed in it. It is impossible to disinfect a plant without destroying it. In addition, in the ordinary air of an apartment there are more than enough various microorganisms. Melt water is useful, it does not contain salts and is effective for rooting.
Do I need to change the water in the container with cuttings? No, you should not change the water under the cuttings, but only add it if necessary. They often die after changing the water. Probably, some kind of stable environment is formed in the glass from the waste products of the plant, promoting root growth. Saintpaulia leaves and passionflower cuttings that have already produced roots sometimes die after changing the water. Place an activated carbon tablet in the water to inhibit putrefactive processes.
How many cuttings can be placed in one glass? A little, 1 or 2. The more capricious the plant, the less. In a large mass, cuttings usually all die. As soon as one begins to rot, this process will affect everyone else.
Rooting in the ground
Some plant species do not grow roots in water. They can stand in it for a month and not sprout a single root, while they will appear in the ground within a week. The general rule is this: plants from swamps and tropical rainforests take root easily in water; species from arid areas are best planted in the ground.
Soil for rooting
What soil should I use to root cuttings? Loose, able to retain moisture well, with neutral acidity. For most crops, a simple mixture is most often used: peat in half with coarse sand. Or other inert soil that is not prone to rotting. You can add perlite and vermiculite and coconut fiber to peat. Sphagnum moss is useful, it has disinfectant properties and retains water well. Too loose soil dries out quickly.
Soil sterility. The soil for rooting cuttings of indoor plants should not contain fungal infections and insect pests. Many flower lovers steam garden soil, fry it or freeze it. The safest thing to do is buy ready-made soil at garden centers and add roasted sand to it. This purchased land is treated with fungicides and insecticides, which reliably protects the plants for some time.
Soil acidity. The acidity of the soil affects rooting. Usually they buy soil with neutral acidity from the store. Most types of indoor plants take root best in it. Hydrangeas need acidic soil; their cuttings root most effectively in slightly acidic soil. The general rule for most plants is this: the acidity of the soil for rooting should be close to that required for an adult plant of this species, but slightly closer to neutral.
Rooting dishes
Disposable plastic cups are good for rooting cuttings. If one cutting rots, the rot will not spread to other cuttings. Through the transparent walls you can see the emerging roots. Be sure to make a drainage hole in the bottom of the cup. It is advisable to place a little perlite or pieces of polystyrene at the bottom to allow excess water to drain freely.
The downside of the cups is their small volume. If you missed a glass when watering, the cutting may dry out.
Conventional seedling boxes or special pallets (cassettes, trays) with cells are convenient for rooting a large number of cuttings. In the boxes, moisture is distributed more evenly, the cuttings are arranged more compactly and are easier to care for.
For small cuttings, plastic food containers with a transparent lid are considered the most convenient option. They are quite rigid, the lid is easy to open when ventilated, and it is easy to make drainage holes in them.
When choosing dishes for rooting, follow these rules:
- If the plant does not tolerate transplantation well, take cups;
- If there are a lot of cuttings, their survival rate is low - choose boxes or pallets.
Cuttings of citrus fruits, myrtles, and oleanders are usually planted in boxes. The crowns of these plants need to be shaped and pruned, after which many branches remain, quite suitable for cuttings. Not all of them will take root, but some of them will still take root.
How to plant a cutting
The question seems simple. At first sight. Some plants have roots that grow along the entire length of the stem buried in the soil. The deeper you plant, the more roots there will be. In others, they appear only from a thickening at the cut site, and new shoots will grow from there. This place should not be very deep from the soil surface.
A universal method is to plant cuttings not strictly vertically, but obliquely, at approximately an angle of 45 degrees. Then the lower end of the cutting is not located deeply, and a fairly large part of the shoot is in contact with the soil.
In summer, the surface of ponds, lakes and other standing waters is covered with a bright green film. This phenomenon is explained by the massive development of small, very original aquatic flowering plants from the duckweed family floating on the surface of the water.
Lemnaaceae are highly reduced plants. The vegetative body is represented by a small green leaf-shaped plate floating on the surface of the water or submerged in water.
Representatives of this group are duckweed, Duckweed trilobed multi-root.
Fig. 17 1 – small duckweed; 2 – polyroot; 3 – duckweed trilobed
Lesser duckweed has modified shoots - flat plates up to 3 mm wide and 4 mm long. Leaves do not develop on them; a root with a clearly visible “pocket” at the end extends from each blade into the water. The leaf of duckweed is green above and below, and lens-shaped in cross-section. The plant blooms very rarely. Vegetative propagation occurs by separation of daughter shoots. It breeds abundantly in summer in stagnant, slightly polluted water bodies.
Duckweed trilobed widespread in bodies of water with stagnant or slowly flowing water. The stem plates are narrow-lanceolate, translucent, floating under the surface of the water. Individual shoots are connected to each other, since duckweed actively branches shoots and numerous groups are formed. During flowering, the shoots float to the surface of the water.
Common polyroot also floats on the surface of the water in the form of a plate, but on the lower side it has a bunch of reddish or white adventitious roots. The plate of the plant is flat on both sides, bright green on top, reddish-brown below, sometimes almost purple, its size is 0.3 - 0.5 cm. Polyroot blooms rarely, propagates by lateral shoots - plates. With the onset of cold weather, polyroot and duckweed sink to the bottom of reservoirs, where they remain until next spring.
Common watercolor, or frogfish, is found in stagnant and slowly flowing waters, reed thickets in shallow waters. Watercolor is an elegant plant with round leaves floating on the water. The stems and numerous roots extending from them are immersed in water. The plant is dioecious - the flowers are unisexual, white, on long stalks. During the summer, the plant reproduces quickly using long shoots, like strawberry tendrils. In the second half of summer, wintering buds - turions - form at the water's edge, sinking to the bottom with the onset of cold weather. The plant received its name for its beauty during the flowering period. At this time, it is a real decoration of reservoirs.
Plants submerged in water
The structure of this group of plants is especially characteristic of an aquatic environment. The roots and shoots of these plants are completely submerged in water, but flowering occurs above the water. Some of them float freely in the water (pemphigus, duckweed), others take root in the soil of the reservoir (many pondweeds, elodea). This group also includes algae (spirogyra, cladophora, chara, etc.).
The most widespread in our reservoirs is e Lodeya Canadian, or water plague. Its shoots reach 3 m and are immersed in water. When they come into contact with the ground, they take root using adventitious roots. Elodea is a dioecious plant, but we have predominantly pistillate (female) specimens. Reproduction of this plant occurs intensively by lateral shoots. Each side shoot, having separated from the plant, can give rise to new thickets of elodea (hence the name water plague).
Leads an underwater lifestyle curly pondweed. It grows in running water. In early June, underwater creeping rooting shoots develop from pondweed buds overwintering at the bottom of the reservoir, producing numerous vertical branches. Their length can reach 1 m. The edges of the elongated and thin leaves of pondweed are wrinkled in a peculiar way (hence the name “curly”), which protects the leaf from the mechanical effects of flowing water. There are no stomata in the leaf epidermis; metabolism occurs across the entire surface of both the leaf and the stem. There are many air cavities in the stem and leaf of pondweed. The flower spikelet of pondweed rises above the water, and the fruits and seeds ripen in the water.
In stagnant shallow bodies of water you can find an interesting insectivorous plant - pemphigus vulgaris. On the shoots of this plant immersed in water, strongly dissected leaves are formed, some of which are transformed into small bubbles. When small water insects fall into these bubbles, they die there and are gradually digested, enriching the bladderwort with the substances necessary for its life. In mid-summer, bladderwort blooms. Yellow flowers rise above the water, and fruits ripen above the water.
Plants immersed in water have a sanitary value for water bodies - they clean them of carbon dioxide and enrich them with oxygen.
Illustrative material for this excursion is given below.
Fig. 18 Plants of reservoirs:
A – Canadian elodea; 1 – pistillate flower; B – bladderwort: 1 – inflorescence; 2 – trapping bubbles; 3 – greatly enlarged trapping bubble; B – floating pondweed; G – curly pondweed.
Fig. 19 Plants of reservoirs
A – frog watercolor; B – pure white water lily: 1 – transition of stamens into petals; 2 – fruit; B – yellow capsule: 1 – sepal; 2 – petal; 3 – stamen; 4 – pestle; 5 – leaf scars on the rhizome; D – aloe vera: 1 – daughter vegetative shoot; D – duckweed trilobed; E – small duckweed; F – multi-root.
Fig. 20 Coastal plants
A – common arrowhead: 1 – emergent leaves; 2 – staminate flower; 3 – pistillate flower; 4 – stolon with nodule; B – plantain chastuha; B – umbrella susak; G – marsh marigold.
Fig. 21 Coastal plants:
1 – common reed; 2 – lake reed; 3 – umbrella susak; 4 – broadleaf cattail; 5 – chastuha plantain; 6 – common arrowhead; 7 – water slug; 8 – broadleaf gracilis; 9 – simple headband; 10 – riverine horsetail.
Fig.22 Aquatic plants
1 – pierced-leaved pondweed; 2 – floating pondweed; 3 – pure white water lily; 4 = yellow capsule; 5 – Canadian elodea; 6 – water pine; 7 – common watercolor, or frogwort; *8 – hard-leaved buttercup; 9 – duckweed trilobed; 10 – pemphigus vulgaris; 11 – brilliant pondweed; 12 – dark green hornwort.
LITERATURE:
1.Filonenko-Alekseeva A.L., Nekhlyudova A.S., Sevostyanov V.I. Field practice in natural history: Excursions into nature: Textbook. aid for students higher textbook institutions.-M.: Humanit. Ed. VLADOS Center, 2000.
2. Gulenkova M.A., Krasnikova A.A. Summer field practice in botany. M.: Education, 1976
3.Novikov V.S., Gubanov I.A. School atlas-identifier of higher plants. M.: Education, 1985.
4. Jaromir Pokorny. Trees around us. Prague: Artia, 1980
5. Dorokhina L.N., Nekhlyudova A.S. Guide to laboratory exercises in botany with basic ecology. M.: Education, 1980.