PLANTS

From Big Medical Encyclopedia

PLANTS (Plantae, Vegetabilia) — the part of the organic world consisting of organisms with autotrophic food, based on use of energy of the Sun by photosynthesis.

Distinctiveness of R. are existence at plant cells of the dense cover constructed, as a rule, of cellulose of special organellas (chlorolayers) containing a chlorophyll in to-rykh it is carried out photosynthesis (see), and also the strong partition of a body leading to sharp increase of its surface. This feature of R. is connected with character of their food (absorption from the environment of gaseous and liquid components — air and water with the nutrients dissolved in it). Rubles meet heterotrophic type of food rather seldom. It generally saprophytes (see) and parasites (see).

PLANTS play extremely large role on Earth. Without R. existence of fauna, including and the person is impossible; R.'s life activity created the atmosphere and the soil of Earth, and R. are an initial link in a long mains circuit of animal organisms. Rubles have also a certain medical value (see. Medicinal plants , Noxious plants ).

R.'s kingdom is divided into three large subkingdoms (departments, or types): lavers (Rhodobionta), the real seaweed (Phycobionta) and the higher plants (Embryobionta) numbering in general apprx. 500 000 separate types. Along with this classification all R.' division into the lowest and the highest is traditionally used. To the first group bacteria, all seaweed, slime fungus, mushrooms and lichens, and are carried to the second — mosses, club mosses, ferns, gymnospermous and angiospermous Rubles.

In human life the higher PLANTS, first of all seed and hl have the greatest value. obr. angiospermous, or floral, R. K to them belong almost all R. cultivated by the person. These are grain (rye, wheat, barley, rice, corn, oats, etc.)? leguminous (haricot, peas, lentil, etc.), sugar-bearing (sugar beet, sugarcane), maslyanichny (sunflower, peanut, olive, etc.), and also various fruit, berry, vegetable and other cultivated plants. The river, cultivated by the person, coffee, cocoa are a source of raw materials for production of fabrics (a cotton, flax, hemp, jute, a kenaf and other fiber plants), tea. Plants are used in livestock production. River — a source of construction material, cellulose (see), and also other products, useful to the person (various pitches, essential oils, dyes, pharmaceuticals, etc.).

The most extensive group of modern gymnospermous R. is made by coniferous. The open (naked) arrangement of a seedbud is characteristic of them.

Feature of Angiospermae is existence of the fruit developing from an ovary of a flower. The flower serves for formation of pollen and macrospores. After fertilization, Krom is preceded by pollination, the germ concluded in a seed is formed. Seeds are in fruits. At the majority of Angiospermae in one flower men's and female sex cells ripen or men's and pistillate flowers are formed on one plant. In this case speak about an odnodomnost. At nek-ry types men's and pistillate flowers are formed on different plants (a poplar, a hazel grove, a sea-buckthorn, etc.). Such R. call gonochoristic.

Processes of blossoming, fertilization and formation of fruits are very difficult and demand participation in pollination of wind, insects, birds and even mammals. All cereals, many species of trees belong to typical anemogamous R. (an alder, a birch, a hazel grove, etc.). Floral R.' most in the course of evolution had various devices for pollination by means of insects: bright coloring and aroma, connection of small flowers in inflorescences, noticeable for insects (e.g., at umbrella R.), etc.

Is engaged in studying of plants botany (see).

See also Animals , Life .



Bibliography: Vent F. U. V flora, the lane with English, M., 1972; Life of plants, under the editorship of A. A. Fedorov, t. 1 — 5, M., 1974 — 1980; Zhukovsky P. M. Cultivated plants and their relatives, L., 1971; Levina R. E. Sketches on a systematics of plants, Ulyanovsk, 1971, bibliogr.; Engler A. Syllabus der Pflanzenfamilien, Bd 1 — 2, V., 1954 — 1964.


T. A. Zaletayeva.

Яндекс.Метрика