I Medicinal plants are a source of medicinal raw materials. Dried, less often freshly collected parts (leaves, grass, flowers, fruits, seeds, bark, rhizomes, roots) of medicinal plants are used as medicinal raw materials.… … Medical encyclopedia

Medicinal plants- Swamp calamus. Swamp calamus. Medicinal plants are a source of medicinal raw materials. Dried, less often freshly collected parts (leaves, grass, flowers, fruits, seeds, bark, rhizomes, roots) are used as medicinal raw materials... First aid - popular encyclopedia

Fibrous plant of the nettle family; same as Rami...

J. local A plant of the nettle family that wounds with a sting [sting I 1.], sting 1.. Dictionary Efremova. T. F. Efremova. 2000... Modern explanatory dictionary of the Russian language by Efremova

NETTLE HERB- Herba Urtica dioica. Stinging nettle (Urtica dioica L) is a perennial herbaceous plant of the nettle family. Properties. Nettle leaves collected during the flowering of the plant are used. They contain vitamin K, glycoside urticin, tannins and... Domestic veterinary drugs

A plant from the genus Beehmeria of the nettle family. More often, R. is called snow-white Boehmeria, otherwise Chinese nettle, V. nivea, or R. white (sometimes R. green is distinguished as a special species, B. viridis, or V. utilis). R. perennial... Big Soviet encyclopedia

- (Chinese). A genus of nettle that produces spinning fiber of the highest quality. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. RAMI Chinese nettle, delivers high quality spinning fiber. Nettle or ramie...

Unchanged; Wed [Malay] Subtropical plant of the family. nettle, with long and strong fiber (used in the manufacture of ropes and textiles of special strength). * * * ramie is a subshrub of the nettle family. Grown in China, Japan,... ... encyclopedic Dictionary

Y; and. A herbaceous plant with stinging hairs on the leaves and stems. Burn your hands with nettles. The garden is overgrown with nettles. Hot k. Cabbage soup made from young nettles. ◊ Dead nettle. A weedy herbaceous plant with small white flowers and leaves similar to... ... encyclopedic Dictionary

- (or nettle), nettle, pl. no, female A weed from the nettle family with skin-burning hairs on the leaves and stems. Burning edge. Nettle cabbage soup. ❖ White or dead nettle is a plant from the Lamiaceae family, with small white flowers,... ... Ushakov's Explanatory Dictionary

See ANTIAR. Dictionary of foreign words included in the Russian language. Chudinov A.N., 1910. ANCHAR The sap of the poisonous upas tree, which the inhabitants of the Indian archipelago use to poison their arrows. Explanation of 25,000 foreign words that came into use in... ... Dictionary of foreign words of the Russian language

General information about nettles

Nettles (lat. Urticaceae) are annual and perennial herbs or shrubs, occasionally climbing. More than 50 genera and about 1000 species, distributed mainly in the tropics. The most famous representatives are nettles, which have extremely strong stinging properties, Laportea, as well as Pilea and Soleirolia, which are common in indoor culture. Nettle, a genus of herbs in the nettle family. The stems and leaves are covered with stinging hairs. 40-50 species, mainly in temperate zones Northern and (less often) Southern hemispheres. Perennial stinging nettle and annual stinging nettle are widespread. The leaves are rich in vitamins. Young shoots of nettle are used for soups and salads, as feed for livestock and poultry. Medicinal plant.

Botanical description. The leaves are entire, opposite or alternate, often covered, like the stem, with stinging hairs and equipped with stipules. The leaf arrangement in primitive forms is opposite, while in more advanced forms it is two-rowed and alternate due to the reduction of one leaf in each pair of opposite leaves. Often this leaf does not disappear completely, in which case anisophily characteristic of the family is observed. Flowers are unisexual, monoecious or dioecious. The perianth is poorly developed, sometimes it is not there at all. The inflorescences are usually unisexual, varied in shape - capitate, paniculate, catkin-shaped. Before pollination begins, the filaments of the stamens are tightly coiled; their sudden straightening leads to the release of pollen. The stamens in the bud are rolled inward and unfold elastically, and the anthers burst, throwing out dust in the form of a cloud. This is especially pronounced in the genus Pilea. The ovary contains one straight ovule. The fruits are usually small, dry (nut-shaped), but some are fleshy and berry-shaped. Mulberry Laportea (Laportea moroides) - similar to raspberry fruits. The fruit is a sac with one seed.
Subfamily nettles (Urticeae). The most well-known members of the family. Burns inflicted by tropical representatives of the tribe, especially Laporteans, can even lead to fainting and death, which can be felt for many months. However, despite this, laportheas are defenseless against cattle, and the berry-bearing urea (Urera baccata) even develops many spines. Representatives: Nettles (Urtica), Laportea (Laportea), Girardinia (Girardinia), Urera (Urera).

The subfamily Procrideae includes more than 700 species of herbaceous, rarely succulent plants, usually living under the canopy of tropical rainforests of Southeast Asia, in wet habitats, near streams, in rock crevices and gorges. Representatives: Pilea (Pilaea), Elastosoma (Elastosoma), Pelionia (Pelionia).
The subfamily Boehmerieae unites 16 genera and about 250 species of herbaceous plants with large serrated, crosswise opposite leaves. Inflorescences develop in the leaf axils. The tribe contains many spinning plants with very long fibers. Representatives: Boehmeria, Pipturus, Maoutia, Pouzolzia, Leucosyke
Subfamily Forskaoleae. The most archaic, interesting from an evolutionary point of view, group of nettles, very specialized. Analysis of their ranges suggests that all three genera have existed for at least 75 million years, and were part of the Cretaceous subtropical flora of the coasts and islands of the ancient Tethys Sea. Representatives: Australina, Drougetia, Forsskaolea.
Subfamily Parietarieae. A small (5 genera and about 30 species) group, the most advanced in the family, includes herbaceous and shrubby plants with entire, mostly alternate leaves. There are many pioneer plants and weeds among the wallflowers. Distribution: Southern Europe, Mediterranean, Transcaucasia. Representatives: Parietaria, Gesnouinia, Hemistylis, Rousselia, Soleirolia.

The most common genera of the nettle family are:
Nettle (Urtica)
Laportea
Pilea
Parietaria
Rami (Boehmeria)
Soleirolia
Urera

Healing properties and use in folk medicine. Nettle has been used as a medicinal plant since ancient times. Ibn Sina wrote about nettle as a medicinal plant: “Crushed nettle leaves stop nosebleeds..., a medicinal bandage (from nettle) with salt helps reduce nerves... Nettle seed eliminates asthma, standing breathing and cold pleurisy.” Russian medicine used nettle back in the 17th century and highly valued it as a good hemostatic agent. In scientific medicine, nettle is used as a hemostatic agent in the form of a decoction, infusion, fresh juice and powder for uterine, pulmonary, kidney, intestinal, hemorrhoidal bleeding, and for hypovitaminosis. Nettle preparations are also used for atherosclerosis, anemia, cholecystitis, gastric and duodenal ulcers, for the treatment of non-healing purulent wounds and ulcers, for the normalization of the ovarian-menstrual cycle, for dysentery, and anemia. Nettle is a good remedy for spring fatigue, improves metabolism, and increases the body's resistance. It can be used as an antidiabetic agent due to the presence of secretin, which stimulates the formation of insulin. The drug "Allocholum" contains nettle extract along with garlic extract, dry animal bile and activated carbon. Used as a choleretic and laxative, 1-2 tablets 3 times a day after meals.

1. Characteristics of the nettle family

medicinal plant nettle

Nettle family-- URTICACEAE

Systematic position

In traditional taxonomy, the family has own order-- nettles (Urticales):

Division of flowering plants (Angiosperms) (Magnoliophyta, Angiospermophyta)

Class dicotyledons (Magnoliopsida, Dicotyledones)

Hamamelid subclass (Hamamelididae)

Order Nettles (Urticales)

Elm family (Ulmaceae)

Mulberry family (Moraceae)

Hemp family (Cannabaceae)

Family Cecropiaceae

Nettle family (Urticaceae)

Nettles include about 60 genera and more than 1000 plant species, distributed mainly in the tropics. They grow mainly in the temperate climate zone in the Northern and (less often) Southern Hemispheres.

The main difference between nettles in the order system is the orthotropic and basal or almost basal ovule, the straight spade-shaped embryo and the predominance of herbaceous life forms, less often shrubs, trees with soft wood and lianas, the latter including most African species.

The leaves of nettles are simple, usually with 3 veins at the base; one of their characteristic features is the abundance of cystoliths - whitish formations impregnated with calcium carbonate. The shape of cystoliths (pointed, rod-shaped, oval, crescent-shaped, club-shaped, stellate, F-shaped, etc.) is more or less constant for certain taxa and often serves as a good diagnostic feature in the taxonomy of species and genera of the family.

The leaves of primitive forms of nettles are arranged oppositely on the shoots; in more advanced forms, the leaf arrangement may become double-rowed, due to the reduction of one leaf in each pair of opposite leaves. There are many intermediate stages along the path of this transition. Most often, one of the opposite leaves does not disappear completely, but only decreases in size, and then we are faced with a very characteristic phenomenon for nettles - anisophidly - the development in one node of leaves that are unequal in size and sometimes in shape.

The inflorescences of nettles are of the topaceous type, varied in shape: capitate, paniculate, catkin-shaped. Sometimes they are bisexual and contain one or several female and several male flowers, but more often the inflorescences are unisexual.

The evolution of the family proceeded mainly along the line of simplifying the structure of organs and reducing their parts. The features of reduction in nettles are especially clearly manifested in the flower: the gynoecium has completely lost its dimeric structure, and the number of flower parts can be reduced to the limit. In the tribe Forscaoleaceae, for example, the male flower usually consists of one stamen surrounded by a perianth, the female flower contains only a gynoecium, its perianth is completely reduced, and an undivided perianth rarely develops.

Nettles are wind-pollinated plants. Their stamens in the buds are usually bent inward, but by the time they pollen, the filaments instantly straighten, the anthers crack from the shock and throw out pollen. This device for dispersing pollen is a characteristic feature of nettles.

Nettles bear fruit abundantly, and in some species the seeds can develop asexually as a result of apomixis. For example, a number of species of elatostema (Elatostema acuminatum, E. sessile) have almost no male flowers, however, female flowers produce fruits with full seeds. Observations on the formation of seeds have shown that in these plants the micropyle is overgrown long before the embryo sac matures and the embryo arises from an unreduced egg without pollination and without fertilization.

In most nettles, the most common method of distributing fruits is zoochory, however, in a number of species of Elatostema and Pilea, the fruits are catapulted in a peculiar way, and the role of the catapult is played by staminodes. During the period of flower dusting, staminodes are barely noticeable, and only at the time of fruiting do they significantly increase in size. At this time, the staminodes are bent inward and support the fruit partially hanging over them. As soon as a separating layer forms on the stalk and the connection between the fruit and the plant weakens, the staminodes straighten with force and eject (catapult) the fruit. In this case, the fruits fly away at a distance of 25-100 m from the mother plant. However, in most nettles the most common route of fruit dispersal remains zoochory.

Nettles very often reproduce vegetatively by rooting stems, underground stolons, root suckers, tubers, etc. In herbaceous succulents, this method of reproduction often prevails over the seed method.

The family is usually divided into 5 tribes: Urticeae proper, Procrideae, Boehmerieae, Forsskaoleae and Parietarieae.

In terms of the number of species in the tribe, the genus Nettle (Urtica) predominates, containing approximately 50. The representatives of the nettle tribe, which unites stinging plants, are the most well known in the family. The Latin name of the tribe Urticeae (as well as Urtica, Urticaceae and Urticales), derived from the word uro - burning, was given to it for the many burning hairs covering the leaves and stems of plants. Stinging nettle hairs have stinging cells (per 1 mg of its mass there are up to 100 stinging cells) containing a caustic liquid of a complex chemical composition; it contains histamine, acetylcholine, formic acid. The burning hair looks like a capillary tube ending in a small round head. The upper part of the hair becomes silicified and breaks off when touched, the sharp edges of the hair pierce the skin, and the contents of the stinging cell are injected into the wound. The result is a painful burning sensation - a nettle burn.

Representatives: nettle (Urtica), laportea (Laportea), girardinia (Girardinia), urera (Urera).

Tribe Procrideae

The largest tribe in the family, it includes more than 700 species of herbaceous, rarely succulent plants, usually living under the canopy of tropical rainforests of Southeast Asia, in wet habitats, near streams, in rock crevices and gorges.

Representatives: Pilea (Pilaea), Elastosoma (Elastosoma), Pelionia (Pelionia).

Tribe Boehmerieae

A pantropical tribe that unites 16 genera and about 250 species of herbaceous plants with large, serrated, crosswise opposite leaves. Inflorescences develop in the leaf axils. The tribe contains many spinning plants with very long fibers.

Representatives: ramie (Boehmeria), pipturus (Pipturus), mautia (Maoutia), pouzolzia (Pouzolzia), leucosyke.

Tribe Forskaoleae

The most archaic and interesting group of nettles from an evolutionary point of view, very specialized. Analysis of their ranges suggests that all three genera have existed for at least 75 million years, and were part of the Cretaceous subtropical flora of the coasts and islands of the ancient Tethys Sea.

Representatives: Australina, Drougetia, Forskaolea.

Tribe parietarieae

A small (5 genera and about 30 species) group, the most advanced in the family, includes herbaceous and shrubby plants with entire, mostly alternate leaves. There are many pioneer plants and weeds among the wallflowers. Distribution: Southern Europe, Mediterranean, Transcaucasia.

Representatives: Parietaria, Gesnouinia, Hemistylis, Rousselia, Soleirolia.

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Nettle family (Urticaceae) (I. A. Grudzinskaya)

Nettles include about 60 genera and more than 1000 plant species, distributed mainly in the tropics. The family is usually divided into 5 tribes: Urticeae proper, Procrideae, Boehmerieae, Forsskaoleae and Parietarieae.

The main difference between nettles in the order system is the orthotropic and basal or almost basal ovule, the straight spade-shaped embryo and the predominance of herbaceous life forms.

The evolution of the family proceeded mainly along the line of simplifying the structure of organs and reducing their parts. The features of reduction in nettles are especially clearly manifested in the flower: the gynoecium has completely lost its dimeric structure, and the number of flower parts can be reduced to the limit. In the tribe Forscaoleaceae, for example, the male flower usually consists of one stamen surrounded by a perianth, the female contains only gynoecium, its perianth is completely reduced, and an undivided perianth rarely develops. The inflorescences of nettles are of the topaceous type, varied in shape: capitate, paniculate, catkin-shaped. Sometimes they are bisexual and contain one or several female and several male flowers, but more often the inflorescences are unisexual.

The fruits of nettles are small, dry (nut-like), but in some species they are surrounded by a succulent cover of a fleshy calyx that grows after flowering, making the fruit look like a drupe or berry. In Urera baccifera, a small tree common in the tropical forests of America, the overgrown calyx is brightly colored, which makes the fruit even more similar to a berry. Similar to the berries are the reddish-orange fruits of the Procris species, the fleshy part of these fruits is formed by the receptacle. The reddish-purple fruits of Laportea moroides are very similar to the fruits of mulberries or raspberries, however, unlike them, the fleshy part of the fruit in this plant arose mainly due to the growth of the peduncle.

Nettles bear fruit abundantly, and in some species the seeds can develop asexually as a result of apomixis. For example, a number of species of elatostema (Elatostema acuminatum, E. sessile) have almost no male flowers, however, female flowers produce fruits with full-fledged seeds. Observations on the formation of seeds have shown that in these plants the micropyle is overgrown long before the embryo sac matures and the embryo arises from an unreduced egg without pollination and without fertilization.

In most nettles, the most common method of distributing fruits is zoochory, however, in a number of species of Elatostema and Pilea, the fruits are catapulted in a peculiar way, and the role of the catapult is played by staminodes. During the period of flower dusting, staminodes are barely noticeable, and only at the time of fruiting do they significantly increase in size. At this time, the staminodes are bent inward and support the fruit partially hanging over them (Fig. 148). As soon as a separating layer forms on the stalk and the connection between the fruit and the plant weakens, the staminodes straighten with force and eject (catapult) the fruit. In this case, the fruits fly away at a distance of 25 - 100 m from the mother plant. However, in most nettles the most common route of fruit dispersal remains zoochory.

Nettles very often reproduce vegetatively by rooting stems, underground stolons, root suckers, tubers, etc. In herbaceous succulents, this method of reproduction often prevails over the seed method.

The leaves of nettles are simple, usually with 3 veins at the base; one of their characteristic features is the abundance of cystoliths - whitish formations impregnated with calcium carbonate (Fig. 148). The shape of cystoliths (pointed, rod-shaped, oval, crescent-shaped, club-shaped, stellate, V-shaped, etc.) is more or less constant for certain taxa and often serves as a good diagnostic feature in the taxonomy of species and genera of the family.

The leaves of primitive forms of nettles are arranged oppositely on the shoots; in more advanced forms, the leaf arrangement may change to double-rowed-alternate, due to the reduction of one leaf in each pair of opposite leaves. There are many intermediate stages along the path of this transition. Most often, one of the opposite leaves does not disappear completely, but only decreases in size, and then we are faced with a very characteristic phenomenon for nettles - anisophylly - the development in one node of leaves that are unequal in size and sometimes in shape (Fig. 148).

The most well known in the family are representatives of the nettle tribe, which unites burning plants. The Latin name of the tribe Urticeae (as well as Urtica, Urticaceae and Urticales), derived from the word uro - burning, was given to it for the many burning hairs covering the leaves and stems of plants. Stinging nettle hairs have stinging cells (there are up to 100 stinging cells per 1 mg of its mass), containing a caustic liquid of a complex chemical composition; it contains histamine, acetyl choline, formic acid. The burning hair looks like a capillary tube ending in a small round head (Fig. 147). The upper part of the hair becomes silicified and breaks off when touched, the sharp edges of the hair pierce the skin, and the contents of the stinging cell are injected into the wound. The result is a painful burning sensation - a nettle burn.

Burns caused by tropical representatives of the tribe, especially arboreal laportheas, sometimes lead to serious consequences. The stinging effect of Laportea urentissima, native to Southeast Asia, is so strong that it can cause the death of a child. The arboreal Laporteas of the Philippines are also notorious: the Lusopian Laportea (L. Luzonensis) and the semi-closed Laportea (L. subclausa). The stinging hairs of the Australian giant laporthea (L. gigas), a large tree from the tropical rainforests of North-Eastern Australia, are incredibly painful; the pain from her burn often leads to fainting and is felt for several months. The same burns, accompanied by tumors of the lymph nodes, are caused by the Australian succulent Laportea mulberry, growing in our greenhouses as an herbaceous plant, and the shrubby Laportea light-leaved (L. photiniphylla) from the Fiji Islands, New Caledonia and Australia. The burns of Laporteizina (L. aestuans), a small creeping herbaceous plant of the Antilles, are unpleasant. The touch of the herbaceous Girardinia heterophylla, common in Indochina, is very painful.

Stinging hairs protect the plant from being eaten by animals, but, of course, they do not save it from all enemies. The leaves of the Australian tree laportea, for example, turned out to be harmless to cattle, the leaves of nettles are eaten with impunity by snails, etc. It is therefore not surprising to see additional protective devices in plants. Urera berry-bearing, for example, in addition to stinging hairs, develops many spines on its shoots; in addition, it is one of the few nettles that has milky juice. Laporte and nettles also have laticifers, but they contain a colorless liquid and not milky juice, like most mulberries.

In terms of the number of species in the tribe, the genus predominates nettle(Urtica), containing approximately 50 species of herbaceous plants, and the tropical genus Urera (35 species), represented by various life forms: herbaceous plants, shrubs, softwood trees and lianas, the latter including most African species. In the USSR, only species of nettles from the Urticeae tribe are widespread (Fig. 147). Everyone knows nettle as a stinging weed, but not everyone knows that common nettle (U. dioica) - most useful plant our temperate flora (Fig. 147). It is rich in vitamins A, C, K and mineral salts, its leaves and young shoots are edible, they are used raw (mashed) and boiled. In folk medicine, it is successfully used as a hemostatic agent for internal bleeding, as well as for vitamin deficiency. Nettle seeds are rich in oil, the leaves are successfully used to feed silkworms, yellow dye is obtained from the roots, and green dye is obtained from the leaves. Nettle has long been known as a spinning plant; in past times it was a common raw material for making handicraft fabrics. The bactericidal effect of nettle is well known to fishermen, and they use it to preserve fresh fish (the insides of the fish are removed and stuffed with nettles).

An invariable companion of human habitation - stinging nettle - is distributed cosmopolitanly; stinging nettle (U. urens) also has a cosmopolitan habitat - smaller and more stinging annual plant(Fig. 147). These plants also differ in the nature of the distribution of flowers: in stinging nettle both male and female flowers are located on the same plant, in dioecious nettle - usually on different plants. The hemp nettle (U. cannabina, Fig. 147) differs sharply from them with 3-5 divided leaves, similar to hemp leaves. Its range extends across the Asian part of the USSR, Mongolia, Japan and China. Another unique type of nettle is ball-shaped nettle (U. pilulifera) - a small bluish plant with whole leaves and spherical inflorescences on long stalks located in their axils. Its habitat covers the Mediterranean, in our country it grows in the Crimea and the Caucasus, occasionally found in the south of the European part of the USSR.

In addition to nettles, in the USSR Girardinia cuspidata and Laportea bulbifera are occasionally found from this tribe; fleshy tubers develop in the axils of the leaves of the latter, with the help of which it reproduces vegetatively. Both species are common in the Far East. It's high herbaceous plants with stinging hairs, like nettles.

The largest tribe of procrisids includes more than 700 species of mostly herbaceous, often succulent plants, living mainly under the canopy of tropical rainforests or in humid habitats in semi-deciduous tropical forests - near streams, under rocks, in gorges. The tribe is dominated by the pantropical genus Pilea (about 400 species), uniting herbaceous plants with intra-axillary fused stipules, predominantly a 3-lobed perianth in female flowers (Fig. 148) and clearly defined cystoliths of various shapes on the leaves and stems.

The genus Elatostema is widespread in the tropics of the Old World, including (together with Pellionia) about 300 species of herbaceous plants. Very close to it is the small (16 - 20 species) paleotropical genus Procris; its representatives, mainly herbaceous or shrubby epiphytes with succulent leaves and stems, grow on the trunks and lower branches of trees. Procris are common on the islands of Indonesia and the Philippines, but in general the range of the genus extends from tropical Africa, through the tropics of Southeast Asia, the islands of Micronesia and the Solomon Islands to Polynesia.

In the USSR (in the Far East), 3 types of pili with crosswise opposite leaves grow from procrisaceae. These are the small (up to 7 cm high) Pilea rotundifolia, Japanese Pilea (P. japonica), also common in Japan and China, and the perennial herbaceous Mongolian Pilea (Pe mongolica), growing in Transbaikalia.

Pili species and other members of this tribe are better known to us as graceful, widely cultivated ornamental plants. Particularly attractive are the variegated forms, climbing plants with reddish leaves - small herbaceous succulents, similar in habit to the tree bl. 39). This is small-leaved Pilea (P. microphylla) - an American plant, widely used as an ornamental plant in the Old World. In Southeast Asia, in addition, the sour shoots of this pili are eaten.

Pilea smallifolia blooms profusely, its millimeter-long pinkish flowers (Table 39) open at different times, and the anthers also crack one by one, suddenly throwing clouds of yellowish pollen into the air. It seems to shoot out pollen, which is why this graceful little pilea is called the “artillery plant.”

The Bemeriidae tribe has a pantropical distribution (only individual species extend into regions of warm-temperate climate) and unites about 16 genera and about 250 species of mostly herbaceous plants with characteristic large and usually coarsely toothed leaves, arranged crosswise opposite. In the axils of the leaves there are capitate or catkin-shaped inflorescences. In some tropical Bemerias, the thread-like axes of female inflorescences sometimes reach 50-100 cm in length and look like the beards of lichens; more often, the flowers are collected on the inflorescence axis into separate spherical heads, making the overall inflorescence look like a string of beads.

Among the Boehmeriaceae there are many spinning plants, and the most valuable of them is considered to be ramie (Boehmeria nivea) - a large herbaceous plant with whole, white-silver leaves below. Silky fiber is obtained from its bast, which is used to make a variety of fabrics. The fibers of ramie are several times longer than those of other spinning plants, they reach 500 mm. Ramie comes from China, but has long been cultivated in many countries, including the USSR (mainly in Central Asia and Transcaucasia), and has not yet lost its importance in the textile industry. Fibers from green bemeria (B. viridis) and representatives of some other genera of the tribe (Pipturus, Maoutia, Pouzolzia, Leucosyke) are also used for yarn.

The small tribe Forscaoleaceae, consisting of 3 genera, has long attracted the attention of researchers with its extremely colorful flowers, which are not at all similar in appearance to nettle flowers. Their small, few-flowered inflorescences are also unique: they are enclosed in a wrapper that imitates a perianth and look like individual flowers.

This tribe is one of the most specialized in the family and at the same time, undoubtedly, very ancient, as evidenced by the areas of its genera. The genus Australina (Fig. 149), for example, is distributed in South Africa, in the mountains of Northeast Africa, South Australia, Tasmania and New Zealand. Huge gaps in the range of Australina indicate its antiquity and suggest that in the distant past the distribution of the genus was associated with the southern continent of Gondwana, which broke up more than 75 million years ago and gave rise to South America, Africa, India, Australia and Antarctica. The genus Drougetia appears to have similar connections; its members now grow naturally in Southern and Eastern Africa, Madagascar and India.

Completely different ancient connections are shown by the distribution of the genus Forsskaolea. Its modern range extends from the Canary Islands through North Africa, Southern Europe, Western Asia and Afghanistan to India and thus covers a number of areas of the Ancient Mediterranean floristic sub-kingdom of Holarctis. It is likely that this genus spread in the Cretaceous period as part of the Cretaceous subtropical flora along the shores and islands of the ancient Tethys Sea.

A small tribe of postenaceae (5 genera and about 30 species), the most advanced in the nettle family, includes herbaceous and shrubby plants with entire, mostly alternate leaves, their inflorescences are single multi-flowered, often with involucres, the perianth of the female flowers is tubular.

The tribe is dominated by the genus Parietaria, which differs somewhat from other nettles in its distribution mainly in the warm-temperate zone and the clear predominance of bisexual flowers. Wallworts, usually tender herbaceous plants, sometimes woody in the lower part, grow in damp places in shaded areas, among rocks and stones; often appear on screes, along mountain slopes reaching an altitude of 3000 m above sea level (Central Asia). Their range covers mainly the temperate regions of Eurasia, but the weak wallflower (P. debilis) is distributed much more widely and is found on all five continents. Its range is often cited as an example of the extraordinary breadth of the species’ natural distribution. However, it is possible that wallflower was introduced into a number of countries as a result of human activity.

Among the wallflowers there are many pioneer plants, and weeds are not uncommon. Their seeds are usually distributed by animals. The seeds of the Lusitanica plant (P. lusitanica) are carried by ants; they harvest the fruits of this plant for the sake of elaiosomes - oily appendages into which the bases of its perianths turn.

In the USSR, 5 types of wallflower are common; they grow in the south of the European part, the Caucasus, Central Asia and the Far East (stoneweed - P. officinalis, wallflower Lusitanian, wallflower of Judaea - P. judaica, wallflower - P. alsinifolia and wallflower small-flowered - P. micrantha, which some researchers identify with weak wallflower).

In the Ancient Mediterranean floristic subkingdom, the remaining 4 genera of the tribe are also widespread, and the tree-like Gesnouinia arborea, growing on the Canary and Azores Islands, corresponds in tropical America (in the Antilles and in the northern regions of South America) as well as the tree-like forms of representatives of the genus Hemistylis (Hemistylis) , the herbaceous Rousselia humilis growing on the Antilles is replaced in the Mediterranean of the Old World by the herbaceous soleirolii.

Soleirolia is a small climbing plant with densely seated small rounded leaves and single flowers, the involucres of which are covered with curved clinging hairs (Fig. 149). It is widespread in Southern Europe and is readily cultivated in our greenhouses and gardens, mainly due to its ability to quickly spread vegetatively and cover the free area with a green decorative carpet.

Order nettles (Urticales)

Elm family (Ulmaceae) (I. A. Grudzinskaya)

The elm family unites two rather separate groups of woody plants, differing in the structure of flowers, pollen grains, fruits, embryos, leaf anatomy, basic chromosome number, composition of chemical substances, etc. These two groups are usually given the rank of subfamilies or, less often, independent families (Grudzinskaya, 1967 ). In this edition we accept them as the subfamilies Ulmoideae and Celtidoideae.

In the elm family there are only woody plants with simple alternate leaves and rapidly falling stipules. Their axillary inflorescences combine small wind-pollinated flowers with a simple cup-shaped perianth, divided into 4 - 5 (9) lobes; they are opposed by approximately the same number of stamens. The ovary is superior, unilocular, developing into a single-seeded, indehiscent fruit.

The elm subfamily is a small homogeneous group, the most isolated and most primitive in the nettle order. It unites 6 genera, which include about 50 species of woody plants. The central place among the elms belongs to the elm genus (Ulmus), which includes more than 75% of the species of the subfamily, distributed from the temperate to tropical zones of the northern hemisphere.

In all genera of the elm subfamily, even true tropical ones, young developing shoots are covered with bud scales. The flowers are bisexual or bisexual and male, the threads of the stamens in the buds are straight. In the order of nettles, only in the elms it is clearly noticeable that their gynoecium is formed by two fused carpels: in one of them the ovule develops, the other is reduced and remains sterile. The upper parts of the carpels do not grow together and are carried on inside stigmatic surfaces. There is no column. The ovary is unilocular, flattened.

The simplicity of the structure of the elm flower, as well as the entire order of nettles, is secondary. Its simplification was due to the reduction, fusion and loss of individual organs (parts of the stamens, corolla, calyx lobes and carpels). This can be judged by the preservation of a large number of flower parts in primitive groups of species, as well as by the remains of vessels of the conduction system of no longer existing organs. Reduction processes in flowers probably began a very long time ago. In any case, judging by fossil prints, elm flowers, whose age is estimated at 20 - 30 million years, already had a structure similar to the modern one.

In all elm genera, the ovaries are similar in structure, but their transformation into fruits is extremely specific in each genus, as a result of which the fruits themselves differ sharply in shape and structure (Fig. 128). The fruits of our elms and holopteleas (Holoptelea) are winged achenes, but some elms develop wingless fruits. The rest of the elm genera are characterized by nuts: in Phyllostylon brasiliense they end in two narrow unequal wings with ribs along the outer edge and with stigmas on the inner; Hemiptelea davidii has oblique, one-winged, swollen, humpbacked nuts; The nuts of Zelkova species do not have wings, and the water glider (Planera aquatica) has semi-fleshy comb-like outgrowths instead of wings. The fruits are well adapted to be carried by wind. This is facilitated by their wings, large air cavities in the intercellular spaces of the pericarp, the small mass and flattened shape of the fruit, often bordered by cilia, or the enlarged cavity of the seed nest. Zoochoria has no place here of great importance, although animals willingly eat elm fruits.

In a temperate climate, with a sharp change of seasons, elms are usually deciduous summer green plants; in the subtropical and especially tropical zones, semi-deciduous, less often evergreen forms appear among them. Tropical semi-deciduous Holoptelea and Phylstylon usually shed their leaves before flowering, but the duration of their stay in the leafless state varies sharply from year to year and is associated with living conditions and the age of the tree. In Cuba, in some years, young phyllostylon plants retain most of their foliage all year round, and in dry years, mature trees stand without leaves for about 3 months. Zelkova and hemiptelea are deciduous plants, and the elm genus is represented by a whole variety of forms, and from north to south, semi-deciduous ones are added to its deciduous species, and in the tropics also evergreens.

If you trace the seasonal development of elm species from the temperate to the tropical zone, you can notice very interesting patterns not only in the nature of deciduousness, but also in the rhythm of flowering. In elms of the temperate zone, the flowers are formed in the buds already at the beginning of summer, but they bloom only the next year and, thus, remain in the buds for about 10 months. Elms bloom in early spring while still leafless. Further south, in Central Asia and the Mediterranean, elms bloom in February and even in January, and the period the flowers remain in the buds is reduced to about 7 months. In the subtropical regions of America, Japan and China there are semi-deciduous elms that bloom in the fall of the same year. Their flowers remain in the buds for only 3 to 4 months; inflorescences appear in the fall, when many leaves have not yet fallen. Some of the inflorescences appear in the axils of these leaves, which creates the impression of leafy flowering shoots. Finally, further south, in the tropics of Southeast Asia, the evergreen lanceolate elm(Ulmus lanceifolia) blooms in early summer, apparently immediately after the end of flower formation; the time spent in the buds of its flowers is reduced to a minimum.

The inflorescences of elms, holoptely, phyllostylon and gliders are leafless and are formed in specialized buds, which, as a rule, do not bear the primordia of true leaves. On the contrary, the flowering shoots of the zelkova (Fig. 129) and hemipthelia (Fig. 130) species do not have strict specialization. Their flowers are formed together with the leaves in the same buds and bloom in the spring - early summer, immediately after the leaves unfold; The fruits ripen only in late summer or autumn. In elms, as well as in gliders, the formation of fruits lasts about a month and already in late spring - early summer the fruits ripen and fall.

Elm seeds have a flat, straight embryo, protected by a three-layer seed coat (the fourth inner single-row layer is formed by endosperm cells) and a four-layer membranous pericarp. On a moist substrate, seeds germinate within a few days without a dormant period. Developed shoots differ sharply from shoots of adult plants. This phenomenon, known in many plants, is called heteroblastic development. In elms, it lies in the fact that their ordinary shoots have a bilaterally symmetrical structure: the leaf blades are asymmetrical, the stipules are unequal in shape and size, and the leaf arrangement is two-rowed and alternate. The apical bud never forms on the shoots, and after the growth of the shoot stops, its upper part dies. In contrast, in elm seedlings the main shoot is radially symmetrical: the blades of its leaves are more or less symmetrical, the stipules are the same, and the leaves are located crosswise on the shoot opposite. At the top of such a shoot a terminal bud is formed. True, no special bud scales arise in this case, and the protection of the apical growth cone is taken over by the stipules upper leaves, as is typical of many tropical plants that do not form bud scales. These stipules-scales remain on the shoot until the next spring, that is, they live much longer than the leaves, while ordinary stipules of elms fall off much earlier than the leaves - at the beginning of summer.

The peculiarity of the main shoot of a seedling is also that it develops according to the monopodial type and is formed by the apical (in position) meristem. All subsequent shoots, including those that continue the main axis of the plant (trunk), arise due to the activity of the axillary (lateral) meristem; The apical meristem in elms usually dies soon after the formation of the terminal bud of the shoot. The shoot formed from the upper lateral bud grows most quickly and, overtopping the mother shoot, becomes axial. This is a repeating reversal from year to year - characteristic feature growth of the elm trunk and branches, allowing them to be classified as typical sympodial plants.

The shoots of some elms attract attention with peculiar corky growths, especially characteristic of young plants growing in dry, well-lit places. Outgrowths of a completely different type sometimes appear on the trunks of old small-leaved elm trees in xerophytic formations of Eastern Kazakhstan. These are burls - huge influxes of compacted, unusually strong wood. An interesting modification of shortened shoots, transformed into real spines, is characteristic of hemiptelea (Fig. 130) - the only thorny tree among the elms.

Elm leaves, even on the same shoot, can vary sharply in size and shape. This allows them to be most advantageously positioned in relation to the light - in one plane - in the form of a continuous mosaic cover (leaf mosaic). The venation of elm leaves is typically pinnate, marginal, with a powerful midrib and short lateral veins, usually ending in leaf teeth. The surface of the leaves is often covered with soft or coarse hairs, and in some species of elms the leaves below are covered with tiny glandular hairs: pointlike (in our birch barks) or rod-shaped (in the Himalayan hairy elm - U. villosa). The color of these glandular hairs changes as the leaf ages: from colorless in young developing leaves, orange in early summer, red in summer to almost black in autumn.

The root system of elms is powerful, with individual roots going deep and a mass of superficial ones. Large trees sometimes develop plank-shaped roots that perform a supporting function and are so characteristic of trees in tropical rain forests. These roots reach a height of 1.5 m at the point where they emerge from the trunks of tropical holoptels. In temperate zone elms (smooth elm - U. laevis, valley elm - U. japonica), their height is usually 30 - 50 cm, but their type of structure is the same as that of tropical trees. However, according to I.V. Grushvitsky (1955), individual valley elm trees in the south of the Primorsky Territory have one and a half and even two-meter board-shaped roots.

Representatives of all studied elm genera are mycorrhizal plants; mycorrhiza is especially abundant on birch bark roots, which are often covered with peculiar mycorrhizal covers.

The root system is of great importance in the vegetative propagation of elms due to the formation of root suckers. In the hexaploid heptelea David, which produces many seedless fruits, the root-sprout type of regeneration often prevails over the seed type. Often propagated by root suckers and birch trees.

Information about the life expectancy of elms is contradictory, but elms and zelkovas are reliably known to have lived up to 500 years (age individual trees Hornbeam zelkova - Zelkova carpinifolia - in Talysh is determined to be 800 - 850 years old). Such long-livers often reach the maximum sizes for these species: up to 35 - 40 m in height and 3 - 4 m in diameter. Giant elms are also preserved in the riverine forests of the Far East (valley elm), in the tropical forests of Mexico (Mexican elm - Ulmus mexicana) and Southeast Asia (elm lanceolate); Holoptelea integrifolia reaches large sizes in the tropical forests of India. Representatives of other elm genera are small trees, 4–18 m high.

The modern range of the elm subfamily covers a vast territory, within which most genera have a discontinuous (disjunctive) distribution, and the appearance of these disjunctions is usually associated with the Tertiary or Upper Cretaceous.

Paleobotanical data indicate that in the Miocene, in the temperate and warm-temperate floras of the Tertiary Boreal region, corresponding to the territories of modern Eurasia and North America, elms were widespread and represented by a wide variety of forms (genera elm, zelkova, glider). Disruptions in the modern ranges of the tropical genera Holoptelea (Western India - equatorial Africa) and Phyllostylon (Brazil - Caribbean floristic region) confirm the antiquity of these genera and suggest their wider distribution in the past. Even the monotypic genus Hemiptelea, whose modern range is limited to a small area in East Asia, was distributed in Central and Southern Europe in the Miocene - Pliocene.

The water glider is the only modern representative of the genus glider - a relict plant, occasionally found in Florida and adjacent areas of southeastern North America. It grows in ancient forests dominated by swamp cypress (Taxodium distichum), where the soil is covered with water most of the year.

The modern range of zelkova is clearly relict (Japan - regions of Southern and Central China - Transcaucasia - regions of Western Asia - the island of Crete).

Among the elms, only the genus elm has an unbroken (continuous) extensive range, but within its boundaries there are curious disjunctions in the distribution of closely related species of one section. Thus, our European smooth elm (Ulmus laevis) is separated by a transatlantic disjunction from the closely related American elm (U. americana). Morphologically, these species are almost indistinguishable, but have different degrees of ploidy: European - diploid (2n = 28), American - tetraploid (2n = 56). There is a similar disjunction between diploid species: European mountain elm (U. glabra) and American red elm (U. rubra).

In our country, representatives of the elm genus are known as elms, elms, birch barks, and elms. They are usually recognized by their double-toothed, unequal-sided leaves at the base and winged fruits that appear in early summer.

In the broad-leaved forests of the European part of the USSR, the most common are smooth elm and mountain elm - large trees reaching a height of 25 - 27 m. Both species have a large latitudinal distribution range, it is especially large in smooth elm. Stretching from the shores of Lake Onega to the Caspian deserts, its range covers the zone of semi-deserts, steppes, forest-steppes, deciduous forests and dark coniferous taiga.

In the forest-steppe zone, birch bark (U. campestris) is more common - a relatively small edge tree, often attracting attention with cork growths on the branches.

Along the river valleys of the Far East, in broad-leaved and cedar-deciduous forests, huge white-barked valley elms are often found, and small trees of lobed elm (U. laciniata), more common in the mountain forests of Primorye, grow here. In the Far East and Transbaikalia, large-fruited elm (U. macrocarpa, Fig. 131) and small-leaved elm are also common - pioneer species of open habitats, sometimes forming xerophytic woodlands.

Large-fruited elm is a small tree, often developing on rocks and screes as a shrub-like plant, bearing fruit abundantly even at a height of 50-70 cm. Its lionfish are the largest (up to 3-4 cm in diameter), cork growths on young shoots grow in the same plane, which is why the shoots also look winged.

Small-leaved elm (U. pumila) is of great importance in landscaping and protective plantings in arid countries of almost all continents. Its natural range extends from the mountains of the Western Tien Shan through the deserts of Mongolia and China to Transbaikalia and the Far East. In the Gobi deserts it is often the only tree species. Here it is a low-growing tree (2 - 6 m high) with a small crown and a powerful trunk, up to 1 - 1.5 m in diameter. In Eastern Kazakhstan, in the Ili River basin, centenary elms have a height of 8 - 12 m, they reach the same height in the floodplains of the rivers of the Far East and Transbaikalia, but in cultivation, especially along ditches in Central Asia, they can exceed 25 m in height and develop a powerful spreading crown.

Not even a hundred years have passed since the beginning of breeding of this species outside its natural range, but now its “cultural” range encircles the entire northern hemisphere, including certain areas of the southern (regions of Australia and Argentina). In the Great Plains region (North America), small-leaved elm behaves like a native and is included in local floras. In our country, it is a favorite breed in landscaping southern cities and towns all the way from the eastern to the western borders.

Representatives of the elm genus have existed on Earth for tens of millions of years and, judging by fossil finds, have not changed significantly over this period of time, despite repeated and sometimes abrupt changes in living conditions. This speaks of a huge adaptive potential, which is still visible today in the breadth of ecology and the modern distribution of the genus. As characteristic components of deciduous forests, elms also grow in deserts and the Arctic Circle, along dry rivers (oueds) in North Africa and near the equator, in Sumatra and Sulawesi, in the tropical forests of Yunnan, in the mountains of Mexico and in the Himalayas.

Elms are unpretentious plants that tolerate a lack of moisture and excessive flowing moisture; they are able to grow on saline soils, rocky placers and rocks, on riverine sands and pebbles, put up with a lack of heat in the north and its excess in hot deserts, with fluctuations in the water level of rivers and lakes, along the banks of which these trees are most often found. And it is precisely areas with extremely variable environmental factors, which are to one degree or another unfavorable for forest development and tree growth in general, that are most common in cenoses dominated by elms.

In lowland broad-leaved forests, which are optimal for the development of most of our elms, they are found only in small admixtures with the main species, firmly occupying the place of assectant (additional) species. Even in the floodplains of large rivers, where elms often form areas of pure stands, their growth is usually associated with a narrow strip characterized by the most variable water regime, at the junction of floodplain oak forests and thickets of willows or alders. In dry years, this strip is unfavorable for the development of willows, and in wet years - for oak.

Elm trees have long been used for various purposes. The mucous secretions of elm bast have bactericidal properties; they, like the seeds, are used in folk medicine. Valuable technical oil is also obtained from elm seeds. The unripe fruits of small-leaved elm are eaten as salad in China.

In a number of mountainous regions of Asia and Transcaucasia, branches of elm and zelkova are harvested for livestock feed. In the landscapes of these mountainous countries and especially in the Himalayas, mutilated elm trees are not uncommon, the branches of which have been cut off almost to the top of the trunk.

Elm wood has great economic value. Already in fossil human settlements in Europe, houses built from elms were found. In the last century, elm and zelkova wood was widely used as a building material, especially for buildings in water: on piles, in shipbuilding, etc. It is also used for the production of furniture and plywood.

At present, when the reserves of elm wood in natural plantings have significantly decreased, elms bring the greatest benefit as landscaping species and constant components of protective plantings. The speed of growth of elms, their decorativeness, undemanding soil nutrition, ability to withstand lack of moisture and strong winds, significant temperature fluctuations and air smoke have long made them the favorite trees in urban landscaping in the countries of the northern hemisphere.

Elms on streets, in gardens and parks are cultivated throughout Eurasia (small-leaved elm, smooth elm, mountain elm, valley elm, birch bark), in Africa (small-leaved elm, gray elm), in North America(American elm, small-leaved elm, Thomas elm, red elm). In addition to the usual types, a number of unique decorative forms, fixed in culture, are also used in landscaping. These are weeping and pyramidal elms, as well as the famous densely crowned elms - dense elm (U. densa) and Androsov elm (U. androssowii), decorating the streets, gardens and parks of the republics of Central Asia, certain regions of Transcaucasia and Western Asia. Their unusually thick spherical or oblong crown almost does not let through sun rays and provides shelter from the sun at any time of the day, which makes them exceptionally valuable in hot desert areas. Dense-crowned species are characterized by very slow growth, and therefore they are usually grafted onto ordinary birch bark or small-leaved elm trees.

Over the past 60 years, a disease called Dutch disease after its discovery has spread among elms (see pp. 129, 130 of the second volume of Plant Life). All types of elms are susceptible to it (only small-leaved elm is resistant). The most effective measure to prevent the development of the disease is the injection of antibiotics into the trunk of the plant.

The subfamily of hackberry - evergreen, semi-deciduous or deciduous trees, less often evergreen climbing vines, common in the tropics and subtropics of all parts of the world. Of the 9 genera that make up the subfamily (about 80 species), only one monotypic genus pterocelthys(Pteroceltis) does not extend beyond the warm-temperate zone, the remaining 8 genera include mainly tropical plants, and only a few of their species grow in areas of warm-temperate climate.

In terms of most morphological characters and the general level of development, the hackberry species are a much more specialized group than the elm species.

The subfamily is dominated by species with unisexual flowers, although a small percentage of bisexual flowers is common in some. In the warm-temperate zone, frame trees are represented only by monoecious plants, in the tropics - both monoecious and dioecious, and even within the same species one can see different degrees of differentiation of trees according to the predominance of female or male flowers. Ghaetacme aristata, for example, in the tropics of East Africa almost always has dioecious flowers, but in South Africa it more often develops as a monoecious plant. All transitions from monoecy to dioecy were noted in the eastern trema (Trema orientalis), Lamarck's trema (T. lamarckiana), Durand's framework (Celtis durandii), etc.

Male frame flowers are collected in multi-flowered inflorescences in the axils of scaly leaves, female flowers are located higher up the shoot in the axils of green leaves, 1 - 3, or in complex multi-flowered inflorescences.

Unlike the elm subfamily, which are characterized by dry fruits, all frame fruits have one type of fruit - a drupe (Table 36), but its structure, size and shape are varied (Fig. 132).

Frame seeds are usually round, the embryo is bent transversely, folded transversely or curled into a spiral; in mature seeds, the endosperm is preserved, it surrounds the embryo and fills the recesses of its folds; the seed coat is always single-layered, the pericarp is 3-4-layered.

The basic chromosomal number in frame plants is the same as in hemp plants (x = 10). Polyploidy is characteristic, with some species reaching very high degree ploidy ( trema amboinskaya- Trema amboinensis - 16-ploid!).

The leaves of most frame leaves have 3 clearly defined basal veins, which brings their venation closer to the palmate type. In most South American frames, on the underside of the leaf blade, as a result of the growth of the bases of these veins (probably under the influence of mites settling in them), specific structures similar to swollen pockets develop. Finally, the leaves of the framework are characterized by rounded cystoliths and a varied nature of pubescence (in the West Indian Lamarck's trema, up to 4 types of hairs develop on one leaf, including glandular ones).

The main genera of the skeleton subfamily are 2 pantropical genera: framework (Celtis, table 36) and trema (Trema), including more than 85% of all species. Carcass is not only the largest (more than 50 species), the most polymorphic, but also the most widespread genus. Its range encircles the globe in a huge strip, the northern limit of which fluctuates around 40° north latitude, passing through Japan, continental Asia, the Caucasus, Southern Europe and North America; the southern one runs at approximately 35° south latitude through New Caledonia, Eastern Australia, the Cape region of Africa and Southern Argentina. Despite the great polymorphism, the frames retain a single type of structure of flowers, fruits and leaves throughout the entire range. Frame types are either diploid (the number of chromosomes in somatic cells is 2n = 20) or tetraploid (2n = 40) plants. The latter include all species of the USSR, also common in the Mediterranean: Caucasian hackberry (C. caucasica), bare hackberry (C. glabrata), southern hackberry (C. australis), Tournefort hackberry (C. tournefortii). These are deciduous, summer-green trees with smooth light gray bark and a spreading crown, sometimes reaching a height of 30 m, with a trunk up to 3 m in diameter, or growing as small trees and acquiring a shrub-like shape in unfavorable conditions environments (naked frame and Tournefort frame).

The hackberry species occupy different ecological niches and grow in diverse communities. Caucasian hackberry and Tournefort's hackberry are more common in dry forests and arid woodlands, in lowlands and mountains, often rising to an altitude of 2500 - 2800 m above sea level, usually in places remote from the sea. In contrast, southern hackberry and bare hackberry grow primarily in coastal areas. All these species live on open rocky slopes and gorges, among rocks, on screes, along the rocky banks of small rivers or on slopes towards the sea.

The frames of tropical countries are richly represented and varied, where, along with deciduous and semi-deciduous, evergreen plants are also common, and in many of them the bud scales do not develop and the rudiments of the emerging shoot are covered only by the stipules of the covering leaf.

The frames of Australia and especially New Caledonia are very peculiar, distinguished by entire-marginal thick succulent leaves. In the crowded hackberry (C. conferta), which grows in the coastal zone and is common among mangroves, the leaves are collected at the top of the shoot and are sometimes opposite. In the tropics of Asia, Africa and South America, hackberries are included in the communities of evergreen lowland rain forests (White's framework - C. wightii, Mildbred's framework - S. mildbraedii), as well as mountain forests (Durand's framework, etc.). Tropical hackberries also grow in dry evergreen forests, often forming deciduous woodlands (African hackberry - C. africana, entire-leaved hackberry - C. integrifolia).

In the forests of the tropics of the New World disturbed by logging, evergreen climbing vines intensively develop: iguana hackberry (C. iguanaea), spiny hackberry (C. spinosa), Bolivian hackberry (C. boliviensis). In the first years of life, these frames grow as upright trees or shrubs (1.5 - 5 m high); later, their upper branches intensively lengthen and, clinging with curved spines to nearby trees and shrubs, use them as support. The plant thus turns into a climbing vine and retains this appearance until the end of its life.

In warm-temperate climates, hackberries bloom in the spring, almost simultaneously with the blossoming of leaves. Their male flowers open several days earlier than their bisexual and female flowers. The flowers are wind pollinated, and although they are visited by insects, entomophily is not of much importance since there is no pollen characteristic features grains of entomophilous plants and, at the moment of straightening of the stamen filament, instantly pours out into the surrounding space.

The fruits ripen in the fall, by this time inner part The pericarp (stone) becomes very hard, and the mealy outer layer turns from bright yellow (glabrous carcass) to almost black (southern carcass). Carcass drupes are readily eaten by birds and spread by them.

Frame seeds usually germinate in the spring of the next year; seedlings, like those of elms, develop according to the heteroblastic type and in the first year switch to sympodial branching.

Frames grow relatively slowly and live a long time (up to 200, and according to some sources - up to 600 years). However, at present there are few old large hackberry trees. The high value of its wood and its growth mainly in sparsely forested areas entail regular felling of young trees. After felling, trees recover relatively quickly due to intensive growth (from the stump) regeneration.

The frame is often also called stone wood for its hard, strong, heavy (density 0.78) wood. Despite a number of valuable properties, it still does not have much industrial significance and is currently used mainly for small crafts and decorative items. Frames have been grown in arid countries for a long time; these trees are also loved in Central Asia, the Caucasus and Crimea, where they are often used in landscaping villages and cities, as well as in protective plantings.

The genus Pteroceltis, common in Central China, is closest to the frames. Its only species was described by the Russian botanist K.I. Maksimovich and named after the collector of this plant - Pteroceltis tatarinovii. The very peculiar winged fruits of Pteroceltis are often considered as a transitional link between the wingless fruits of the hackberry fruits and the elm lionfish, which gives reason to bring the taxa themselves closer together, however, the similarity of the fruits is only external - this is an example of convergent development. The fruit of Pteroceltis is a true spherical drupe with a very thick, strong endocarp, the outgrowths of which form woody wings, thinning towards the edge. At the top, the wings are widely spaced; between them and isolated from them, unlike elms, there is a column with two stigmas (Fig. 132). Pteroceltis is also a typical representative of the skeleton subfamily in other ways: it has unisexual flowers, drupes with a 4-layer pericarp, a single-layer seed coat, a folded embryo, 3 veins at the base of the leaf, the main chromosome number x is 20. Pteroceltis usually grows along rivers and in rocky places at relatively low altitudes (up to 1200 m above sea level). Most often these are trees 12 - 17 m high, with a spreading crown and short thick trunks with a diameter of up to 1.5 m.

A very interesting and apparently monotypic genus hetakma(Ghaetacme) is distributed in Madagascar and in equatorial and southern Africa. Hetakma spinosa develops as a small tree or shrub 3-7 m high; it has shiny leathery leaves, sometimes ending in a thin point - a spine, unisexual flowers and small fruits with a hard stone. This species is very polymorphic and includes plants with monoecious and dioecious flowers, is represented by heavily pubescent and glabrous forms, spiny and without spines, its leaves are serrated, spiny-toothed or entire. Hetakma spinosa grows in the transition zone from forest to savanna, found in deciduous, semi-deciduous forest and shrub formations, in sclerophyll gallery forests, where sometimes, together with other plants, it forms impenetrable thorny thickets, so characteristic of these countries.

In tropical countries, the genus Trema is widely known, represented mainly by evergreen trees, sometimes shrub-like plants, 2 - 16 m high, distributed on all continents and many islands from lowlands to 2500 m above sea level. They have a sparse, spread-out crown, branched axillary inflorescences bearing numerous small, usually unisexual flowers. The fruits are small fleshy drupes, bright yellow-orange in Trema Lamarck and dark in Trema eastern and Trema parviflora.

Species of the genus Trema are difficult to differentiate, and there is still disagreement among taxonomists regarding their volume and number. Apparently, there are no more than 20 species in the genus, all of them are close and form a polyploid series with the number of chromosomes in somatic cells from 20 to 160.

Tremes are fast-growing, unpretentious plants that live on the edges of evergreen and semi-deciduous forests of plains and mountain slopes, and are common along roads and in clearings. Trema species are common components of secondary plant formations in the tropics, in particular, characteristic representatives of the peculiar secondary formations with tree ferns that develop after fires and logging in the place of rain mountain tropical forests. In Cuba it is a community of Trema micrantha and Cyathea arborea, with a continuous canopy of bracken fern (Pteridium caudatum). Similar plant formations are characteristic of the tropics of the Old World. In Java, for example, there are communities of Oriental Trema and Cyathea contaminans, and in the undergrowth there is Eupatorium inulifolium.

Trema is so far the only genus in the nettle order in which symbiosis with nitrogen-fixing bacteria has been discovered. Nodule bacteria from the Rhizobium group were recently found on the roots of trema eastern, which gives grounds to classify it as a soil-improving plant. Perhaps partly due to this property, trema is readily used on plantations coffee tree and cocoa to create a thin canopy under which these crops are planted.

Very close to the genus Trema and difficult to distinguish from it is the small genus Parasponia, common on the islands of Oceania. Representatives of both genera are typical pioneer plants, noted as the first settlers of lava flows (Bali island).

The genus Aphananthe has a dispersed range covering widely separated areas of tropical and warm-temperate Asia, including Malesia, parts of the Solomon Islands, eastern Australia, Madagascar and Mexico. These huge disjunctions indicate a wider distribution of afananta in the past.

In the tropics of South Asia, Indonesia and Oceania (mainly on tropical islands) the genus Gironniera is widespread, represented by huge evergreen trees of tropical rainforests (Gironniera carcassifolia - G. ceItidifolia), or small, up to 16 m high, drier semi-deciduous trees formations of the tropics (Gironiere semi-equal - G. snbaequalis, etc.).