Horsetail is a herb. Description, features, types and properties of horsetail. Horsetail Horsetail flowering plant
Introduction
Division Equiformes ( Sphenophyta, or equisetophyta), in the past diverse not only at the species, but also at the generic and family levels, now includes a single genus Equisetum. It contains only about 30 species, the history of which can be traced back to the beginning of the Cretaceous period. Some of them like
from the tropics, reach 8 m in height and 4 cm in diameter. But most species are small in size - up to 30 cm in height and 0.5–2 cm in diameter. Horsetails are vascular plants capable of sexual reproduction through spores produced in sporangia at the ends of stems. The cell walls of horsetails contain granules of silica, which they accumulate from the soil solution, which gives their stems rigidity and vertical stability. Horsetails have long been used in folk medicine as a hemostatic and diuretic. Some species, such as wintering horsetail (
Equisetum hiemale
), whose epidermis is particularly rich in silica, were used to polish walls.
Horsetails are distributed almost throughout the globe - from the tropics to the polar latitudes. Their ecology is also diverse - from water-filled swamps to dry sands and rocks (Fig. 1).
Rice. 1. Ecological extremes of horsetails: A – on a rocky substrate; B - in the swamp But most species are small in size - up to 30 cm in height and 0.5–2 cm in diameter. Horsetails are vascular plants capable of sexual reproduction through spores produced in sporangia at the ends of stems. The cell walls of horsetails contain granules of silica, which they accumulate from the soil solution, which gives their stems rigidity and vertical stability.).
External structure
Rice. 5. Vegetative propagation of horsetail: A – appearance; B – view under a microscope
Like other plants, horsetails are capable of vegetative propagation. It is carried out through young shoots formed in the nodes of the rhizomes or in the lower nodes of the stem (Fig. 5).
Rhizomes can also form in the internodes of the stems if for some reason they come into contact with the ground.
Anatomy
At the top of the stem there is an apical meristem, which carries out apical growth. Like other vascular plants, the leaves and twigs of horsetails are formed from the apical meristem. In addition, the intercalary meristem provides intercalary growth at plant nodes. From it, cells are formed that grow the stem not only in height, but also radially (Fig. 6). Therefore, it never has a strictly cylindrical shape - the diameter of the nodes is always slightly less than the diameter of the internodes (Fig. 7).
A cross section of the internode shows that it has a large central cavity surrounded by a cortex, into which numerous bundles of vessels are inscribed (Fig. 8). In the node, on the contrary, there is no central cavity, and its anatomical structure is similar to the structure of the stems of other vascular plants (Fig. 9).
Sclerenchyma cells are rich in lignin. Chlorenchyma cells contain chlorophyll. Epidermal cells have a thick cutinized membrane. Its surface is rough due to silica granules. They are arranged in regular rows so that ridges and grooves are formed between them. Stomata are located in the grooves (Fig. 10). Their structure is similar to the structure of the stomata of other vascular plants.
Rice. 8. Anatomical structure of the internode
Rice. 10. Stomata on a cross section of the epidermis
Bundles of vessels are located under siliceous ridges. They consist of phloem and xylem (Fig. 11, 12). A stele with such a structure is called eustela.
Generative organs
At the top of the vegetative shoots of horsetails there are sporangia collected in strobili (Fig. 4).
Individual sporangia are relatively large and elongated. They are collected on corymbose sporangiophores, or sporophylls (Fig. 13). Each sporophyll contains 5–10 sporangia on the inner side - sacs with spores (Fig. 14). Since horsetail spores are the same size and bisexual shoots grow from them, they are classified as homosporous plants.
The spores have a spherical shape and are surrounded at the equator by elaters - special hygroscopic threads (Fig. 15). On a hot summer day, with low air humidity, the spore elaters in the opened sporangia are in a curled state. However, as soon as the air humidity rises slightly (for example, after rain), the elaters straighten and catapult the spores out.
Once on moist soil, the spores germinate (Fig. 16).
The prothallus growing from the spore is haploid. It has rhizoids and is capable of photosynthesis. Over time, female (archegonia) and male (antheridia) reproductive organs appear on the prothallus. After fertilization of the egg located in the archegonium, a young sporophyte grows from the zygote, giving rise to a new articular plant.
Ferns are a large group of higher plants. The pteridophytes include three divisions: ferns, horsetails and lycophytes.
Ferns are very diverse in appearance, but they all have vegetative organs - root, shoot (stem and leaves) and reproduce by spores. The fern never blooms, it is just a poetic fantasy. Fern leaves grow at the top. Young leaves that have not fully blossomed are twisted in a snail-like manner.
Horsetails are perennial herbaceous rhizomatous plants that look like small Christmas trees. Both the leaves and lateral shoots of horsetails are located in whorls. Fern structure
Horsetails are perennial herbaceous rhizomatous plants that look like small Christmas trees. Both the leaves and lateral shoots of horsetails are located in whorls. What to do.
Consider the spore-bearing fern plant. Sketch its appearance and label the parts of the plant. On the lower surface of the fern leaf, find brown tubercles; they contain sporangia with spores.
What to watch. Examine the sporangia under a microscope.
Prepare for the report.
Horsetails are perennial herbaceous rhizomatous plants that look like small Christmas trees. Both the leaves and lateral shoots of horsetails are located in whorls. Drawings: the external structure of a fern and the accumulation of sori under a microscope. Answer the questions: what is the root system of a fern? How do leaves grow? Justify that ferns belong to higher spore plants.
Horsetails are perennial herbaceous rhizomatous plants that look like small Christmas trees. Both the leaves and lateral shoots of horsetails are located in whorls. Consider the summer growth of horsetail. Locate the rhizome, stem and whorls of leaves located on the side shoots.
Division Equisetae. About 20-30 modern species of horsetails are known. These plants grow on our planet everywhere in areas with different climatic conditions - from Antarctica to Africa. But in North America and Eurasia, in the temperate and arctic zones, the greatest species diversity of horsetails is observed. This plant received the name “horsetail” for its external resemblance to the tails of animals, in particular horses. Horsetails grow in forests, meadows, swampy areas, and near water bodies.
All modern species of horsetail are perennial herbaceous plants with dense stems impregnated with silica, reaching an average height of 1 to 12 m. The largest species is the giant horsetail, found in tropical and subtropical forests with high humidity. Its length can reach 10-12 m. A characteristic feature of all types of horsetail is the presence of stem metamerism, that is, the correct alternation of nodes and internodes. Horsetails have small, scale-like leaves arranged in whorls at the nodes. Lateral branches also form at the nodes of the stem. Photosynthesis occurs in the tissue of green stems and branches, the surface of which is further increased by ribbing. The sporangia are located on hexagonal corymbose sporangiophores connected into apical strobili.
The underground part of horsetails is a branched powerful rhizome, in the nodes of which adventitious roots are formed. Some species of plants in this group, for example, horsetail, have rhizomes modified into tubers, which serve both for the deposition of reserve nutrients and for vegetative propagation.
Horsetails reproduce mainly by rhizomes, forming many twin daughter plants, especially in places with disturbed vegetation, for example, after fires. Vast thickets of these weeds form in pastures and fields that are difficult to eradicate. Acid soil is favorable for the growth of horsetails, where they grow especially quickly and serve as a kind of indicators of soil acidity.
Horsetails are also characterized by reproduction by spores, which are contained in sporangia on sporangiophores. The stem contains spore-bearing zones of sporangiophores or they are packed into strobili at the apex. The gametophyte, or prothallus, looks like a small, short-lived unisexual or bisexual green plant. Also, the gametophyte may have the appearance of a brownish-pink, non-branching shoot, which dies after sporulation. On these growths there are antheridia with spermatozoa and archegonia with eggs. Water is required for fertilization to occur. The resulting zygote gives rise to a sporophyte.
Horsetails are widely used in folk medicine, in particular, horsetail preparations. These drugs are effective for hypertension, gout, and as wound healing agents. Horsetail fertilizer is used to supplement the nutrition of cows and goats to increase milk yield. Many wild animals eat horsetails. Some species of these plants, such as horsetail, are poisonous to farm animals.
Question 1. What is called fabric?
Tissue is a collection of cells and intercellular substance that have a common origin, structure and perform specific functions.
Question 2. What plant tissues do you know?
There are several types of plant tissues: integumentary, basic, mechanical, conductive and educational.
Question 3. What structure do conductive tissues have and what function do they perform?
Conducting tissues are formed by living or dead cells that look like tubes. There are two groups of conducting tissues: vessels and sieve tubes. Vessels are dead hollow cells connected in series, the transverse partitions between them disappear. Sieve tubes are elongated, nuclear-free living cells connected in series to each other. There are quite large holes in their transverse walls.
Question 4. What structure do mechanical tissues have and what function do they perform?
Mechanical tissues are formed by groups of cells with thickened membranes. In some cells, the membranes become lignified. Often the cells of mechanical tissue are elongated and have the appearance of fibers. These give strength to plants.
Laboratory work No. 11. The structure of spore-bearing horsetail.
1. Using a magnifying glass, examine the summer and spring shoots of horsetail from the herbarium.
2. Find a spore-bearing spikelet. What is the significance of spores in the life of horsetail?
With the help of spores, horsetails reproduce in the spring.
3. Sketch the horsetail shoots (see picture).
Conclusion: horsetails, unlike mosses, have a rhizome. Spores, like those of mosses, serve for reproduction.
Laboratory work No. 12. The structure of a spore-bearing fern.
1. Study the external structure of the fern. Consider the shape and color of the rhizome; shape, size and color of the fronds.
The rhizome (underground shoots) grows in the soil parallel to the soil surface. It is brown in color. The heavily dissected green or light green leaves of ferns are called fronds. Fronds grow directly from rhizomes. The length of adult fronds ranges from 20 to 70 cm.
2. Examine the brown tubercles on the underside of the frond with a magnifying glass. What are they called? What develops in them? What is the importance of spores in the life of a fern?
If you look at the underside of a fern frond in summer, you can see small brown tubercles. These are groups of sporangia in which spores develop and mature. Ferns reproduce with the help of spores (this generation is called sporophyte).
3. Compare ferns with mosses. Look for similarities and differences.
Differences: Mosses do not have roots, but ferns have many adventitious roots growing from a rhizome (a modified shoot). The leaves of mosses are small, the leaves of ferns - fronds - have a complex structure. In mosses, spores are located in a capsule on the stalk, in ferns - on the back side of the frond (on the sporophyte). Ferns have vascular bundles in their stems (which gives them a greater advantage over mosses) - this is the result of ferns’ adaptation to a terrestrial lifestyle.
Similarities: there are shoots (stem, leaves). They reproduce by spores. They gravitate toward moist habitats.
4. Justify that fern belongs to higher spore plants.
Ferns are classified as higher spore plants because they reproduce by spores. The body is also divided into stem, root and leaf. A characteristic feature is the presence of a conducting system (tracheids and vessels), which ensures the exchange of substances between the polar parts of the body.
Conclusion: ferns belong to higher spore plants. Ferns also have many adventitious roots that grow from the rhizome (modified shoot). Ferns have spores on the back side of the frond (on the sporophyte). Ferns have vascular bundles in their stems. All this gives ferns an advantage over mosses in nature.
Question 1. Why are mosses, horsetails and ferns classified as higher spore plants?
Higher spore plants are called mosses, mosses, horsetails, and ferns primarily because their body is divided into organs, each of which performs specific functions. Secondly, they all reproduce by spores.
Question 2. Where do they grow?
Moss mosses, horsetails and ferns grow mainly in moist, shady places. Moss mosses grow mainly in pine forests. Horsetails grow in fields, forests or near bodies of water, usually in areas with moist, acidic soil. Ferns are widespread throughout the globe. They grow both on land and in water. Tree ferns are common in tropical latitudes.
Question 3. What is their structure?
Moss mosses have a long creeping stem with many branches covered with small leaves. In summer, spore-bearing spikelets with spores develop on their erect shoots.
Horsetails are perennial herbaceous plants with long branching rhizomes that overwinter in the soil. In spring, brown shoots appear, at the tops of which there are spore-bearing spikelets. Spores ripen in them. Green summer shoots contain chlorophyll.
The strongly dissected leaves of ferns are called fronds. Some ferns have entire fronds. Most ferns growing in temperate climates have rhizomes (underground shoots) located underground parallel to the soil surface. Fronds grow directly from rhizomes.
If you look at the underside of a fern frond in summer, you can see small brown tubercles. These are groups of sporangia in which spores mature.
Question 4. Which plants - ferns or mosses - have a more complex structure? Prove it.
Ferns have a more complex structure than mosses. Because: Ferns have roots that grow from the rhizome. Mosses have no roots, only rhizoids. Mosses have very small leaves, while ferns have complex and large leaves. Ferns have better developed tissues and a conducting system.
Question 5. What is the significance of club mosses, horsetails and ferns?
From the ancient tree-like forms of these plants, millions of years ago, deposits of coal were formed, which serves not only as fuel, but also as a valuable chemical raw material. It produces lubricating oils, resins, coke, plastics, perfumes and many other products.
Moss moss spores were previously widely used in pharmacies in the manufacture of baby powder. The creeping branched shoots of the club moss are very decorative. In metallurgy, casting molds are sprinkled with spore powder, and metal parts easily come off the walls.
Horsetail is a difficult-to-eradicate weed in fields with high soil acidity.
Horsetail shoots are tough, they contain a lot of silica and were previously used in polishing metal products. In some areas of our country, spring shoots of horsetail are eaten (raw, steamed, and as a filling in pies), as well as young leaves of bracken fern.
Think
Why can many types of ferns, also being spore plants, unlike mosses, reach significant sizes?
Because, unlike mosses, ferns have roots that grow from the rhizome and a well-developed conducting and supporting system, which allows them to transport nutrients to great heights.
Quests for the curious
This suggests that fern-like plants grew on land or in water during the Carboniferous period of the Paleozoic era. Because it was the mosses, horsetails and ferns that formed the coal deposits.
Horsetail cabbage soup(Equisetum) are perennial herbaceous plants that grow in wet fields and meadows, swamps and damp forests. Although they differ in appearance from ferns and mosses, they are similar to them in many ways. Horsetails, like ferns, are spore plants. Currently, horsetails do not play a major role in the formation of vegetation cover. Although horsetails often form thickets in places where other plants cannot exist.
The species diversity of horsetails is small - about 30 species. In forests on moist soil, horsetail with highly branched drooping lateral branches is often found. Overwintering horsetail grows on sandy soils and in ravines; marsh horsetail and riverine horsetail grow in wetlands, along the banks of rivers and lakes (Fig. 88).
Horsetail
A typical representative is horsetail (Fig. 87). This is a perennial weed that grows in fields and arable lands. In the soil there is a branched rhizome with adventitious roots and buds, from which above-ground shoots develop every year. When cultivating the soil, pieces of horsetail rhizome do not die, and an independent plant grows from each. Therefore, this weed is very difficult to control.
Structure
Horsetails have unique articulated stems. Leaves are located at the joints. The stem is impregnated with silica, which gives it greater strength.
Under favorable conditions, horsetail spores, like ferns, germinate into small plants, unlike leafy plants. Organs of sexual reproduction are formed on them, in which germ cells mature. In the presence of dripping water, fertilization occurs. A young horsetail plant with a rhizome is formed from the egg.
After the formation of spores, the spring shoots die, and green summer shoots grow from the rhizome, similar to small pine trees (see Fig. 87).
The stems of wintering horsetail contain a significant amount of silica - a hard, well-polishing substance. Therefore, its stems are especially tough and durable. They have long been used for cleaning metal utensils and instead of sandpaper.
Shoots of some horsetails (for example, horsetail) are used in folk medicine as a diuretic and astringent.
