The department is horsetail. About 20-30 modern 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 there is the greatest species diversity of horsetails. This plant received the name "horsetail" for its external resemblance to the tails of animals, in particular, horses. Horsetails grow in forests, meadows, marshlands, near water bodies.
Everything modern species Horsetails are perennial herbaceous plants with dense, silica-impregnated stems reaching, on average, 1 to 12 m in height. The largest species is the giant horsetail, found in tropical and subtropical forests with high humidity. Its length can reach 10-12 m. Characteristic feature of all types of horsetail is the presence of metamerism of the stems, that is, the correct alternation of nodes and internodes. Horsetails have small, scaly 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 additionally increased due to ribbing. Sporangia are located on hexagonal corymbose sporangiophores connected to apical strobili.
The underground part of horsetails is a branched powerful rhizome, in the nodes of which adventitious roots are formed. Some plant species of this group, for example, the 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 areas with disturbed vegetation, for example, after fires. Vast hard-to-eradicate thickets of these weeds are formed on pastures and fields. For the growth of horsetails, acidic soil is favorable, on which they grow especially quickly and serve as a kind of indicators of soil acidity.
Horsetails are also characterized by reproduction by spores, which are enclosed in sporangia on sporangiophores. The stem contains spore-bearing zones of sporangiophores, or they are packed in strobila at the apex. The gametophyte, or outgrowth, looks like a small, short-lived, single or bisexual green plant. Also, the gametophyte can have the appearance of a brownish-pink unbranched shoot, which dies off after sporulation. On these outgrowths are located antheridia with spermatozoa and archegonia with eggs. For fertilization, water is needed. The resulting zygote gives rise to a sporophyte.
Horsetails are widely used in folk medicine, in particular, preparations of the horsetail. These medicines effective for hypertension, gout, as wound healing agents. Horsetail supplements are used to supplement the nutrition of cows and goats to increase milk production. Many wild animals consume horsetails. Some species of these plants, such as marsh horsetail, are poisonous to farm animals.
What are the features of the structure and reproduction of horsetails (horsetails)?
Horsetails are perennial herbaceous plants with a jointed structure. Shoots are divided into nodes and internodes. Leaves are reduced to whole small plates. The stem performs the function of photosynthesis. In the cells of horsetails, silica accumulates, which makes the stem stiff. Horsetails reproduce by spores that form in spore-bearing spikelets. Spore-bearing spikelets are formed either on special spore-bearing shoots (in the field horsetail), or on the tops of vegetative shoots (meadow horsetail, wintering horsetail). The spore-bearing spike consists of an axis on which the sporangiophores are located. The sporangiophore consists of a stem with a hexagonal plate on it. Sporangia are located on the underside of the plate. Spores form in sporangia. In dry weather, spores spill out. A gametophyte (germ) is formed from the spore. It contains antheridia with sperm and archegonia with eggs. After fertilization, a zygote is formed, and from it an embryo and a new plant develop.
Equisetophyta (sphenophyta).
Equisetofita - from the Latin horse bristle. Sfenophyta - the name articulate reflects the structural features of the shoots. The nodes contain an intercalary meristem.
Horsetails, as well as lymphoids, appeared in the Upper Devonian. Palaeozoic, were most widespread in the Late Paleozoic (Carboniferous period) were part of vast forests, were large, treelike, high. Today, there are the last few remnants of a once vast group that died out at the beginning of the Mesozoic.
Modern representatives, these are perennial plants, rhizome, herbaceous, all belong to the same genus of horsetails, the predominant generation in the cycle is the sporophyte, the body of the sporophyte is divided into a well-developed aerial shoot. Its height is from several centimeters to several meters. There is also a well-developed rhizome with adventitious roots.
All horsetails are characterized by a clear division of the stem, lateral branches and rhizomes into nodes and hollow internodes. Branching is whorled.
Horsetail has two types of stems
1.Chlorophyll-free, spore-bearing, rapidly dying off.
2.Green, vegetative.
(Both are longitudinally grooved.)
In other horsetails, such as the forest horsetail, strobilus develops on a vegetative shoot.
The leaves of modern horsetails are very small, in the form of scales or teeth, but their origin is different from the leaves of lycopods. Leaf of a macrophilic line of evolution.
In the extinct horsetails of the class, wedge-leaved, the leaves were relatively large. They had dichotomous venation, their evolutionary development consisted in thickening, convergence, coalescence, reduction.
Due to the fact that the leaves of modern horsetails, the stem took over the small function of the leaves.
Roots are only adventitious, extending from the rhizome.
Spore-bearing spikelet (strobilus)
In the extinct horsetail, strobila had a rather complex structure, in modern ones it is simpler: on the axis of the spikelet sporangiophores are whorled (sporophylls, leaves bearing sporangia), they differ sharply from leaves, are devoid of chlorophyll and carry sporangia. Horsetails are equidistant.
Among the currently living plants, there are no heterosporous ones; the extinct horsetails were heterogeneous. The clinolists, the calomites. Spores in horsetails differ from other spores in higher plants: at the bottom there are 3 membranes, 2 of them are exine and intine. There is a 3rd feather bed (outdoor). Which is divided into 2 ribbon-shaped springs of the eloter (with the ability to move). Depending on humidity the environment they roll up around the spore body or, in wet weather, on the contrary, they unwind and loosen up and a loose spore mass is formed, which can fly out of the sporangium. These spores drop out of the sporangium and germinate in the immediate vicinity of the sporangium. Gametophytes of modern horsetails have the appearance of a lobed or indented upper part of a green plate several millimeters thick. Multi-layered, attached to the soil with rhizoids. For a long time, gametophytes were considered dioecious, although all modern horsetails are equal in size. As a result of artificial cultivation and observation, it was determined that gametophytes are potentially bisexual, but development begins as male and female. On females, antheridia can form with age, on male archegonia they are never formed, so in horsetails there is a morphological equal dispute and physical disparity.
Classification
Horsetail division
1.Class wedge-leaved (had secondary growth, formed thickets, a meter long, ribbed surface, and the ribs passed from one internode to another without alternation, on the stems of the whorls of leaves. In the most ancient, dissected leaves, in the later wedge-shaped plate, stems of a complex anatomical structure, in the center there is a primary xylem (proto and metoxylem) between its phloem rays, between them a cambium, forming a plug in the outer layers of phellogen. 10 cm in length.
2.Class Horsetails
A) Order Calamitaceae (extinct, appeared in the Devonian, the greatest development in the Carboniferous and disappear in the Jurassic period. These horsetail trees. Inhabited the marsh soil from which shoots up to 30 meters high were produced, the stems had gorges and internodes, the ribs of neighboring nodes alternated. rhizomes numerous adventitious roots. Leaves are linear with one vein. Among them were both homosporous and heterosporous)
B) Horsetail order (represented by one family, one genus, in Africa as invasive plants, despite their primitive structure and ancient origin, successfully competes with terrestrial plants.
Horsetail or Horsetail(lat. Equisétum arvénse) is a species of perennial herbaceous plants of the Horsetail genus, Horsetail family ( Equisetaceae). Translated from Latin, the name of this plant means "horse tail", because of the external similarities. Linguists of Russian philology have also noticed the similarities between "horsetail" and the word "tail". The people call horsetail: ponytail, tin grass, panicle, cat's eye, pusher, mop-grass. Horsetail is a harmful weed; it infests all crops in the forest-steppe and forest belt. For growth, it prefers an acidic and well-moistened soil. In arid conditions, the field horsetail goes into ravines or meadows, where it does not pose any threat. Common horsetail is common almost throughout Eurasia (in temperate, tropical and subtropical regions), in North America, from Alaska and Canada to the southern states of the United States.
Description of horsetail
The stems of the plant are hollow, articulated, the average height is about 50 cm. On the nodes of the stems there are serrated sheaths. The field horsetail forms fertile and sterile stems, outwardly they differ. Fertile stems are not branched, juicy, reddish in color, up to 25 cm tall, they appear in early spring. Fertile stems have one elongated spikelet at the tops, which consist of corymbose leaves. These leaves are located on small legs and carry sacs of spores. Sterile stems develop a little later, they are almost twice as high as fertile ones, branched, rigid, with ribbed sheaths. The barren stems are green and have quadrangular branches.
Due to the fact that the field horsetail is a flowerless plant, it reproduces by spores. Spores are extremely small, globular formations. Spores are poured onto the soil from sacs, which open in a spikelet, and are carried in the form of a green powder by the wind. Each spore is equipped with hygroscopic appendages. During germination, the spores form pre-growths that have either female organs with eggs or male organs with sperm. After fertilization, a new plant develops from the egg. The young horsetail forms a shoot that deepens vertically into the soil, forming a rhizome, after overwintering.
In early spring, starting in March, the spores mature and over time the fertile stems die off.
Field horsetail is able to reproduce vegetatively, thanks to underground shoots-rhizomes, which give sterile stems. The horizontal rhizome goes deep into the ground from 60 cm to several meters, depending on the soil layers. Absolutely all parts of the horsetail, from the rhizomes to the stems, consist of joints and easily break at the boundaries of these joints. Even small scraps can give rise to new shoots.
Horsetail field control measure
In the fight against field horsetail, it is necessary to resort to drying wet and damp soils by laying drainage or open ditches. Deep plowing of the soil using liming and enrichment of the soil with mineral salts and manure will also be irreplaceable. In the case of occurrence of rhizomes below the arable layer, all measures in the fight against horsetail should be aimed at depleting the underground parts and creating conditions unfavorable for their development. Destruction of stems by weeding, mowing, peeling, processing will be very effective. chemicals(chlorates).
Horsetail field use
The field horsetail is rich in chemical composition, thanks to which this plant has a healing effect on the human body. Horsetail has a haemostatic, astringent, diuretic, wound healing, anti-inflammatory, bactericidal, antihelminthic and restorative effect. As a raw material for medicines, sterile spring stems (namely, horsetail grass) are used. Raw materials must be collected in the summer, dried under natural conditions under a canopy, in the attic or in special dryers at a temperature of 40-50 ° C. Blanks are stored for up to four years.
It is recommended to use decoctions and infusions of horsetail for cholelithiasis, internal bleeding, and diarrhea. As compresses and lotions, decoctions are used in the treatment of conjunctivitis, boils, ulcers, dermatitis, lichens. For pulmonary diseases medicinal properties horsetail will have a healing effect. Field horsetail is used for bronchitis, cough, tuberculosis. As a mouthwash, horsetail is recommended for inflammation of the gums and in the treatment of sore throats. Through a series of experiments, it was found that common horsetail helps to reduce sugar levels when diabetes mellitus.
To strengthen bones, teeth, hair, nails, it is worth using horsetail medicines. Horsetail perfectly treats acne, makes the skin smooth and elastic.
Despite all the healing properties, horsetail has contraindications for use. You can not use horsetail in any form during pregnancy and lactation, with kidney disease. Before starting treatment, it is imperative to consult with specialists and doctors.
The fields of application of the horsetail are quite extensive. It is used to polish furniture (the stem powder contains a large amount of silica). Horsetail is also used for dyeing wool; after dyeing, wool turns yellow and green. In plant growing and floriculture, horsetail decoction is used to prevent a number of diseases of garden plants and to increase resistance to pests and fungal diseases (black spot of roses, powdery mildew, rust, mites). The prepared broth retains its healing properties for two weeks.
Field horsetail photo
Horsetail
Horsetail, or articulate, or jointed. or wedge-shaped (lat. Equisetóphytina) - a subdivision of higher spore plants of the fern department, previously placed in the now abolished Equisetophyta department.
Horsetails are characterized by the presence of shoots consisting of clearly defined segments (internodes) and nodes with whorled leaves. In this feature, modern and fossil horsetails differ sharply from all other higher spore plants and appearance resemble some algae (charovaceae), gymnosperms (ephedra), or even flowering.
Horsetails are peculiar plants. Many vegetative traits bring them closer to cereals. Apparently, horsetails are the most competitive among ferns, which is explained by numerous improvements in vegetative organs: the stalk of horsetails is articulate and grows in nodes (like in cereals); the epidermis is reinforced with silica; the weight of the stem is lightened by the presence of a central cavity; there are numerous strands of mechanical tissue that increase the strength of the stem; there are air cavities that allow the supply of oxygen to underground and underwater parts; real vessels develop (like in angiosperms); the spores are equipped with special pushing processes (elaters), which help to loosen the spore mass and, consequently, to transport spores by the wind. It is due to these structural features that horsetails, as in the distant Carboniferous period, continue to dominate in some biocenoses - mainly along the banks of water bodies. Horsetails have one more interesting feature: they have different-sex outgrowths, and the development of male or female outgrowths is predetermined by environmental conditions. In general, the worse the conditions, the greater the percentage of male outgrowths that form. Thus, horsetails show a transitional stage from typical equisportiveness to typical heterosporicity.
Appearance
Horsetails include both herbaceous extinct and living plants with stems ranging from several centimeters to several meters long, and tree-like extinct forms that reached 15 m in height and a trunk diameter of 50 cm.
Anatomy
The conductive system of the horsetail stem is represented by an actinosteel or arthrostoles, that is, a jointed stele, consisting of sections alternating with each other along the stem of various structures... The conductive elements of the xylem are represented by tracheids of various types, and in horsetails also by vessels. Floemas consists of sieve elements and parenchymal cells.
Origin and evolution
Horsetails appeared in the Upper Devonian and descended from the now extinct Rhyniales or some plants close to them, but they flourished in the Carboniferous period, when they were widely represented by a variety of woody and herbaceous forms. Together with lepidodendrons and tree ferns, horsetails took a large part in the formation of the Carboniferous forests.
Fossil horsetails (for example, tree-like calamites) reached a height of 25 m, and secondary xylem was found in their trunks. However, in the Permian, their extinction begins, and first of all, arboreal forms die out, so that from the Mesozoic only herbaceous horsetails are known. To date, only the genus Equisetum has survived from this entire large group.
Both extinct and modern horsetails differ from all known plants in shoots composed of separate segments. The name "Articulated" comes from this specificity of the structure of their shoots, which are dissected into well-defined nodes and internodes, easily disintegrating into segments. The articulation is due to the whorled leaf arrangement and the presence of an intercalary meristem in the lower parts of internodes, along which breaking into segments occurs.
For modern horsetails, peculiar leaves are characteristic - their leaf blades strongly reduced to small dark, sometimes green or colorless denticles, and well-defined sheaths have grown together into a common membranous sheath. The reproductive organs of the articulate are characterized by the presence of strobila in the form of stripes, and only in some Paleozoic species - spore-bearing zones. In modern horsetails, the sporangiophores have a scutellous shape, and in the ancient extinct ones, they had a very diverse shape, except for the leaf-shaped one. The overwhelming majority of horsetails are homosporous plants, and only a few extinct species were heterogeneous.
Classification
The subdivision jointed, or horsetail, includes three classes, the evolution of which proceeded, apparently, in independent, parallel paths - two extinct classes: Sphenophyllopsida, Cladoxylopsida and the now existing class Equisetopsida.
