Fertilization of horsetails. Horsetails. Horsetail: properties and contraindications
Date of__________
Class__________
Subject: Structure, reproduction and development of horsetails. The significance of horsetails in nature and human life.
Tasks: 1. To develop knowledge about the structural features and vital functions of horsetails.
2. Develop the concept of the diversity of the plant world using the example of horsetails.
3. Foster elements of environmental culture.
Lesson type: Combined
Equipment: interactive board
During the classes
1. org moment
2. Checking homework a) Frontal conversation with the class
The structure of the club moss.
List the extinct lycophytes (Lepidodendra, Sigillaria, Leuromea, Osteroxylon).
Describe modern lycophytes.
Why do lycophytes reproduce primarily vegetatively?
What groups are lycophytes divided into? Describe them, name their representatives (emosporous - club moss, heterosporous - selyaginella).
The importance of lycophytes (decorative, medicinal, pyrotechnics, production of resins, plastics, formation of coal).
B) Cards: application
C) working with concepts
Define:
Sorus is a collection of sporangia.
Sporophyte is a plant that reproduces asexually.
Gametophyte is a plant that reproduces sexually.
Sporangia are the organs of asexual reproduction of a sporophyte.
Gametangia are the organs of sexual reproduction of the gametophyte.
A spore is a cell of asexual reproduction.
Gamete is a cell of sexual reproduction.
3. new topic:
In science, horsetails are called segmented because of the structure of the stem.
Appendix the structure of horsetail
Filling out the table
Compare the external structure of Horsetail and Moss clubmoss, enter the data into the table.
Table.
Questions
Horsetail
Moss clubmoss
Division of the body into organs
Types of shoots
Stem branching
6.) Conclusion: What is the difference between the external structure of Moss clubmoss and Horsetail?
Like the lycophytes, the ancient horsetails were represented by trees (calamites) or shrubs (cluneifolia). Modern species are exclusively herbaceous plants, represented by one genus - horsetail, and about 25 plant species.
Habitat: terrestrial. The body consists of a rhizome, the shoot is articulated, consisting of nodes and internodes. The nodes contain lateral branches and brown scaly leaves. Shoots of horsetails are spore-bearing (formed in spring) and bear sporangia at the tops, collected in strobili, brown in color; vegetative shoots are formed in summer, green, photosynthesis occurs in the stems.
Reproduction – sexual or asexual. Gametophytes of horsetails are green plates that live independently. The dominant generation is a sporophyte.
Horsetails are homosporous plants; spores are spread by the wind. They carry two springs - elaters, which interlock with each other.
Working with the textbook
Representatives: Horsetail - the most common type,Large horsetail – the largest, listed in the Red Book, found in the Carpathians,Horsetail , Horsetail , Horsetail .
Horsetail meaning:
Formation of coal
Silica stems are used for grinding metal and wood.
Horsetail is an indicator of acidic soils.
Horsetail is a medicinal plant.
Weeds.
Horsetail propagation
application
4. fastening:
Work in an individual notebook
5
. Summing up the lesson.
Today in the lesson we got acquainted with the features of horsetails using the example of the Horsetail and compared it with the clubmoss club-shaped from the lycophytes department.
What questions do you have?
6.
Homework.
Read §____ page ____
Work in the dictionary (intercalary growth, node, internode).
Among the higher spore plants, which include mosses, mosses, ferns and horsetails, the latter have several features in their external and internal structure. The horsetail plant looks like a small Christmas tree with hard side stems. Interestingly, animals do not eat either it or other types of horsetails. This is explained by the fact that plant tissues are impregnated with silicon compounds. The systematic position of the Horsetail genus indicates the fact that their reproduction occurs with the help of spores. Our article will focus on the structure of horsetail, as well as consideration of its use in medical practice as a medicine.
What is alternation of generations?
In the life cycle of a plant, two life forms change cyclically: asexual and sexual generations. The first is represented by a perennial herbaceous plant, the second has the appearance of green plates with a dissected surface with numerous threads. The reproductive organs develop on them: female - archegonia and male - antheridia. The maturation of eggs and sperm, as well as the process of fertilization itself, occurs only in the presence of water. So, to imagine what horsetails are, you must remember that plants exist in two different forms - gametophyte and sporophyte.
External structure
As we said earlier, the asexual generation of horsetail is a plant that has above-ground and underground parts. Thus, the rhizome provides support and promotes vegetative propagation. A large number of adventitious roots extending from it absorb water and minerals from the soil. The rhizome has a large number of thickenings - nodules. It grows deep into the ground. It should be noted that horsetails are indicators of soil acidification. What are soil indicators? These are plants that require a certain concentration of soil solution for normal functioning. In our example, this is an excess amount of hydrogen ions, that is, high acidity of the soil. As it turned out, plants of the Horsetail genus do not live on neutral or alkaline soils, so their favorite places to grow are biocenoses of swampy areas and river floodplains. The most common type of horsetail is horsetail. It is its branches that are harvested as medicinal plant raw materials. Also found are forest horsetail, meadow horsetail (has a triangular stem), and swamp horsetail with a pentagonal stem shape and black edges at the stem nodes. In addition, this species is also highly poisonous.
Vegetative organs
Let's continue to look at the appearance and properties of horsetail. In addition to the rhizome, the vegetative parts of the plant body include stems, leaves and sporangia. They form a sporophyte - an asexual generation, the task of which is to carry out the process of photosynthesis and the formation of reproductive organs - spore-bearing spikelets. The main ground shoot grows from the rhizome; it branches and is divided by nodes, from which lateral branches diverge in the form of a whorl. There are no leaves with a clearly defined leaf blade; they are reduced to colorless scales that grow from the nodes. Therefore, the function of photosynthesis in horsetails is performed by stems containing chlorophyll. Let's continue to study higher spore plants - horsetails. What are spring and summer forms of shoots? It turns out that the axial organ of the plant is ribbed, impregnated with silicon compounds and has a clear differentiation. Thus, spring shoots are light pink in color, incapable of branching and devoid of green pigment and leaves. At their tops sporangia are formed in the form of hard shields resembling spikelets containing haploid spores. Summer shoots are the main and subsidiary stems, which are bright green. They are capable of branching and, thanks to chlorophyll, carry out the synthesis of organic substances: proteins, carbohydrates and fats, and also provide the release of oxygen.
Sporangia and spores
Like other representatives of higher spore plants - mosses, mosses and ferns, horsetails develop organs on the sporophyte plant in which the maturation of asexual reproduction cells - haploid spores - occurs. Spikelets - sporangia of horsetails, have the form of special structures collected together, called sporangiophores. They are derivatives of lateral stems and look like rings, closely pressed to each other. Spores are formed through the process of meiosis and are haploid cells of the same type. Therefore, the question of what horsetails are from the point of view of the structure of their asexual generation - the sporophyte - can be answered as follows: these are homosporous plants. In addition, the spores are equipped with special springs - elaters, which serve as a device for their better distribution. Subsequently, once on moist soil, the spores germinate and unisexual shoots appear, on which male or female genital organs develop separately.
Gametophyte and fertilization process
Haploid spore cells under favorable environmental conditions (sufficient humidity and absence of direct sunlight) begin to form green lamellar structures with filamentous processes along the edges. This is how a growth is formed. Which genital organs, male or female, will form on it will depend on the light and ambient temperature. On the underside of the shoot there are rhizoids that attach it to the soil surface. Antheridia are male reproductive organs that ensure the development of sperm, and archegonia contain eggs. Fertilization occurs in the presence of water. From the resulting zygote, an embryo develops, which subsequently gives rise to the development of the sporophyte - an asexual generation of horsetail, the medicinal properties of which have been known to man for quite a long time. Next we will look at them in more detail.
Application in medicine
One of the most common species, horsetail, is an effective diuretic and hemostatic herbal preparation obtained from the stems. If the functioning of the kidneys and heart is impaired, accompanied by fluid retention in the tissues and the appearance of severe edema, use a decoction prepared in the proportion: 20 g of raw material per 200 g of water. The diuretic effect is explained by the presence of saponin in horsetail shoots and the high content of potassium ions. In addition to them, plant materials contain vitamin C, carotene, equisetrin, calcium and iron ions. Horsetail decoction is used for uterine bleeding, in the treatment of pleurisy, and for inflammatory processes in the ureters and bladder. Pharmacological raw materials can be purchased in pharmacies in the form of an extract, brewing bags or briquettes.
Horsetail: properties and contraindications
The presence in the vegetative parts of horsetail of a large number of microelements, for example, copper, boron, molybdenum, has a positive effect on metabolism in the human body. However, the high concentration of alkaloids, glycosides and saponin determines not only the astringent, anti-inflammatory and diuretic properties of the plant, but can also cause a number of negative symptoms. For example: diarrhea, nausea, heaviness and pain in the epigastric region. Horsetail extract should be used with caution in the treatment of patients with gastric and duodenal ulcers. A prerequisite for taking medications is not only a strict dosage - no more than half a glass, but also the frequency of use (no more than 3 times a day), as well as compliance with the main rule - using a decoction or extract an hour after meals.
The role of horsetails in ecosystems
What is the significance of horsetails in nature? Giant extinct species of tree-like higher spore plants: horsetails, mosses and ferns, which lived in the Carboniferous period of the Paleozoic era, caused the formation of coal reserves in the bowels of the earth. Modern species of plants of the genus Horsetails are much smaller and distributed in different climatic zones, especially in floodplain meadows and swamps, as well as in coniferous forests. As we said earlier, horsetails thrive on acidic soils; many species, for example, horsetail, clog crops and pastures for domestic animals, since they are inedible for them. In everyday life, the hard branches of horsetail, containing silicic acid and its salts, were previously used as an abrasive for cleaning heavily soiled kitchen utensils.
In our article we examined the properties, structure and significance of horsetails in nature and human life.
The development cycle of horsetail is dominated by sporophyte- an adult, perennial plant consisting of rhizomes, fixed in the soil adventitious roots. In spring, it grows from the buds of the rhizome onto the soil surface. spore-bearing, chlorophyll-free vertical the escape(stem) with a whorled arrangement of reduced (small) leaves, ending in a spore-bearing spikelet ( strobile). The spore-bearing spikelet itself in its structure has axis, on which umbrella-shaped spore-bearing leaves (scutellums on stalks) are located - sporophylls. On the lower side of the sporophylls, facing the strobilus axis, there are from 5 to 10 sporangia. In sporangia as a result of reduction division meiosis cells sporogenous tissue(2n) haploid, morphologically identical, but different sexes are formed disputes(male and bisexual). The spore shells have special outgrowths - elaters, which are twisted spirally around the spores when wet, and unfold when dry. This allows the spores to cling to each other and spread in groups. After the spores ripen, the spore-bearing leaves of the strobile open, the sporangia burst and the spores are carried by the wind. Due to the content of chloroplasts in the spores, they quickly (within 3 weeks) lose their germination capacity. Once on moist muddy soil, groups of spores germinate into chlorophyll-bearing gametophytes in the form of lobed plates fixed in the substrate rhizoids. Gametophytes reach sexual maturity 3-5 weeks after germination. On male gametophytes, smaller in size, are formed antheridia- male gametangia, in which multiflagellates are formed spermatozoa. On bisexual gametophytes, more dissected in shape, archegonia(female gametangia) develop before antheridia, which increases the likelihood of cross-fertilization. For sperm to reach the eggs located in the archegonia, it is necessary water. On one gametophyte, several eggs can be fertilized at once, from which they further develop embryos, there are young sporophytes. The embryos are attached with their feet to the abdomen of the archegonium and receive from the gametophyte the necessary nutrients for development, forming a rudimentary root, stem and bud. After formation, the embryonic root begins to grow, is fixed in the soil, and the young sporophyte is detached from the gametophyte, which dies after some time. After sporulation spring(spore-bearing) shoots die and green rhizomes grow from the buds assimilation shoots. Assimilation shoots have a vertical stem with a whorled arrangement on it lateral branches And leaves underneath them. They perform the function of forming organic compounds during photosynthesis and accumulating them in the rhizome. At the end of the growing season, the assimilation shoots die off, leaving a rhizome that overwinters in the soil.
Rice. 34. Diagram of the life cycle of horsetail
Rice. 35. Life cycle of horsetail
Moss - department of higher spore plants, represented by 1200 species. They are characterized by the presence of a developed conducting system, a root-shoot type of structure of sporophytes and a thallus structure of gametophytes, asexual reproduction by spores and vegetative reproduction by above-ground shoots.
A prerequisite for their growth is increased soil moisture. Therefore, on the banks of reservoirs, in swamps, in damp meadows and in forests, club mosses, like horsetails, can predominate among other herbaceous vegetation. What is the significance of horsetails in human life and how did people learn to use this group of plants?
Features of horsetails
Modern species of this plant have very modest sizes. Growing in temperate latitudes of the northern hemisphere, horsetails reach a height of sixty centimeters to one meter. Varieties inhabiting regions with tropical climates are, of course, large in size.
Horsetails are difficult to confuse with others. Their shoots consist of internodes and nodes, due to which a peculiar stem consisting of segments grows. It is designed to perform the main function in the life of a plant - photosynthesis.
The underground part of horsetails also has a jointed structure. The rhizome easily breaks in the part where the nodes are located, giving the opportunity for the birth of young shoots. It is for this reason that horsetails quickly colonize areas where favorable conditions exist for their growth.
In addition to the vegetative one, they can spread by spores. The shoot on which they ripen appears only once - in the spring.
Silica accumulates in all cells of the plant body, due to which horsetails avoid mechanical damage. The plant is not eaten by insects, shellfish, or vertebrates. At first glance, it may seem that the importance of horsetails in human life is also small. But it turns out that this is not at all the case.
From the past of plants
The forests mainly consisted of giant club mosses, ferns and horsetail plants. It was thanks to them that the primary layers of soil began to form. This is a special formation, without which further life on the planet could not have its modern forms.
The importance of horsetails in human life and in nature is very great. These green giants at one time did the job of saturating the Earth's atmosphere with oxygen. The life of all creatures on the planet today depends on its sufficient content.
The importance of horsetails and mosses in human life can be understood if you know that coal is also a product of the vital activity of these plants. Deposits of valuable combustible substances were discovered precisely in those places where billions of years ago horsetails, mosses, and ferns, which in those distant times had not only herbaceous, but also tree-like forms, were rampant.
Horsetails in human life
The species of these plants, being representatives of modern fauna, are mainly defined by humans as weeds with poisonous properties. It is known that in pastures where horsetails are found, cases of poisoning of domestic animals by this plant are possible.
Its accidental use can be fatal. For this reason, hay meadows, where horsetail began to spread, gradually cease to be used for their intended purpose.
Today, the importance of horsetails in human life is quite important only in the field of pharmacology. The plant is used in the production of diuretics and hemostatic drugs. Traditional healers also find horsetail widely used.
Types of horsetails
The evolutionary path that horsetails have traveled is very long. It is a proven fact that this is one of the oldest plants on Earth. Today there are several of its species - meadow, field, forest, wintering, swamp, riverine. Only a small number of species can be added to this list.
Sometimes in modern classification all horsetails are divided into two groups. The first includes forest, riverine, meadow, swamp, and field. The second group includes branched, polychaete, reed, and wintering.
Modern research into the properties of horsetail
Studying the chemical composition of plants of both groups and finding possibilities for their use is the main task of scientists. Research is carried out not only in the laboratory, but also through experiments and observations in nature.
It has now been proven that horsetails belonging to the second group have high feeding qualities. The same can be said about some types of plants of the first group. They are eaten by wild boars, deer, and horses.
It turns out that under the influence of certain temperatures the percentage and composition of the chemical elements of plant parts changes. In connection with the latest scientific data, there is a need to reconsider the meaning of horsetail in human life, since its use may become much wider in the near future.
Theory for preparation for block No. 4 of the Unified State Exam in biology: with system and diversity of the organic world.
Moss moss
Moss-moss- one of the most ancient divisions of higher spore plants. Currently, they are represented by a relatively small number of genera and species, the participation of which in the vegetation cover is usually insignificant. Perennial herbaceous plants, usually evergreen, resembling green mosses in appearance. They are found mainly in forests, especially coniferous ones.
There are about 400 species, but only 14 are common in Russia (club-shaped moss, ram-moss, double-edged moss, etc.).
The structure of mosses
Lycopods are characterized by the presence of shoots with spirally, less often oppositely and whorled leaves. The underground parts of the shoots of some lycophytes have the appearance of a typical rhizome with modified leaves and adventitious roots, while in others they form a peculiar organ bearing spirally arranged roots and called a rhizophore (rhizophore). Roots of lycophytes are adventitious.
Nutrition and reproduction of mosses
Sporophylls may be similar to ordinary vegetative leaves, sometimes different from them. Among the lycophytes there are equi- and heterosporous plants. Homosporous gametophytes are underground or semi-underground, fleshy, 2-20 mm long. They are bisexual, saprophytic or semi-saprophytic, and mature within 1-15 years. Gametophytes of heterosporous unisexuals, non-green, usually develop within several weeks due to the nutrients contained in the spore, and upon maturity do not protrude or protrude slightly outside the spore shell. The reproductive organs are represented by antheridia and archegonia: in the former, bi- or multiflagellate sperm develop, and in archegonia, eggs develop. Fertilization occurs in the presence of drip-liquid water, and a sporophyte grows from the zygote.
Sporophyte club moss is a perennial evergreen plant. The stem is creeping, branched, produces vertical branched shoots about 25 cm high, densely covered with leaves that look like elongated pointed scales. Vertical shoots end in spore-bearing spikelets or apical buds. On the shaft of the spore-bearing spikelet there are sporophylls with sporangia on the upper side. The spores are identical, contain up to 50% non-drying oil, and germinate very slowly. The gametophyte develops in the soil in symbiosis with a fungus (mycorrhiza), which, receiving carbohydrates, amino acids and phytohormones from the vascular plant, makes water and minerals, especially phosphorus compounds, available for absorption and absorption by the plant. In addition, the fungus provides the plant with a larger absorption surface, which is especially important when it grows in poor soil. The gametophyte develops over 12-20 years, has rhizoids, and does not have chloroplasts. However, in some species it develops on the soil surface, then chloroplasts appear in its cells.
Gametophyte bisexual, shaped like an onion, acquires a saucer-shaped shape as it develops, and bears numerous antheridia and archegonia. Mature antheridia are almost completely immersed in the gametophyte tissue or slightly protrude above its surface. The archegonium consists of a narrow abdomen immersed in the tissue of the gametophyte and a long or short neck protruding above its surface. Antheridia usually mature before archegonia. The zygote germinates without a dormant period and gives rise to an embryo. Vegetatively propagated by parts of the stem and rhizome. Some club mosses also have specialized organs for vegetative reproduction: brood nodules on the roots, brood bulbs or buds on the tops of shoots.
Development cycle of clubmoss: A - sporophyte; B - gametophyte; 1 - creeping shoot with adventitious roots; 2 - ascending shoots; 3 - stalk of spore-bearing spikelets; 4 - leaves: ascending shoot (a) and stalks of spore-bearing spikelets (b); 5 - spore-bearing spikelets; 6 - sporolists: view from the ventral (c) and dorsal (d) sides; 7 - sporangia; 8 - disputes; 9 - germinating spore; 10 - archegonium; 11 - antheridium; 12 - fertilization; 13 - fertilized egg; 14 - development of a new sporophyte on the gametophyte.
Equisetaceae (Horsetails)
The living species are exclusively herbaceous plants ranging in height from a few centimeters to several meters.
In all types of horsetail, the stems have a regular alternation of nodes and internodes.
The leaves are reduced to scales and arranged in whorls at the nodes. Lateral branches are also formed here.
The underground part of horsetails is represented by a highly developed rhizome, in the nodes of which adventitious roots are formed. In some species (horsetail), the lateral branches of the rhizome turn into tubers, which serve as a place for deposition of reserve products, as well as organs of vegetative propagation.
The structure of horsetails
Horsetails are herbaceous plants with annual above-ground shoots. A small number of species are evergreen. The size of horsetail stems varies greatly: there are dwarf plants with a stem 5-15 cm high and a diameter of 0.5-1 mm and plants with a stem several meters long (in the polychaete horsetail the stem reaches a length of 9 m). Tropical forest horsetails reach a height of 12 m. The underground part is a rhizome, creeping, branched, in which nutrients can be deposited (tubers are formed) and which serves as an organ of vegetative propagation. Aboveground shoots grow at the top. Summer shoots are vegetative, branched, assimilating, consist of segments, with well-developed internodes. Whorled and also dissected branches branch off from the nodes. The leaves are inconspicuous and grow together into toothed sheaths that cover the lower part of the internode. Silica is often deposited in the epidermal cells of the stem, so horsetails are a poor food.
Spring shoots are spore-bearing, non-assimilating, unbranched, and spore-bearing spikelets are formed at their apex. After the spores mature, the shoots die. The spores are spherical, with four springy ribbons, greenish, germinate into shoots, unisexual - male or female. There are cases when antheridia and archegonia appear on the same prothallus. From the fertilized egg, a pre-adult grows, and then an adult horsetail.
Horsetails often make up a significant percentage of grasslands in meadows and wetlands; common in acidic soil. Most often, we have horsetail, meadow horsetail, marsh horsetail, marsh horsetail and forest horsetail.
Horsetails reproduce sexually. The sexual generation is the gametophyte (prothallus). Antheridia and archegonia are formed on gametophytes. Multiflagellate sperm develop in antheridia, and eggs develop in archegonia. Fertilization occurs in the presence of drip-liquid water, and a sporophyte grows from the zygote without a rest period.
