The number of the family of cereals. Perennial and annual cereal weeds

CEREALS,matlikovaya (Gramineae, Poaceae), a family of narrow-walled monocotyledonic plants. This is a very large and complex taxonomy group in which it was isolated from two to 12 (now they are usually 5 or 6) submenses that combine approximately 700 genera and 10,000 species. This family includes plants having a large economic, environmental and historical meaning, in particular wheat, rice, corn, rye, barley, oats, sugar cane, bamboo and many pasture herbs.

Structure.

According to morphology, the cereals are so peculiar that a number of special botanical terms are used to describe them.

Stem and leaves.

The stem of cereal, called solomina, throughout, except for the swollen, separated by regular intervals of nodes, usually hollow, although there are exceptions, for example sugar cane and some types of bamboo subfamores. Plots of the stem between adjacent nodes are called interstices. As a rule, cereals - herbs, i.e. Their fabrics are soft, unwanted, but are also known for tree forms, in particular among bamboo. The leaves are narrow, with parallel veins, usually seated, without a pet, are departed one by one from each node alternately in different directions, located on the stem in two opposite rows.

The typical sheet consists of three main parts: base, or vagina covering the stem; rented from the plates stem; Small film or hair outgrowth - tongue (ligules) separating the vagina from the plate. The leaves of some cereals have ears - paired, usually blade, sometimes lanceal or sickle lateral outgrowths at the place of the compound of the plate and the vagina.

Roots.

The root system of cereals urine, i.e. Without the main central axis, formed by numerous subtle roots, a beam separated from the bottom of the stem. By origin, they are apparent, as well as supporting roots, beginning with some cereals over the ground. Fastening the plant in the soil often contributes to the adhesive - the formation of a plurality of roasting shoots, components of a loose or dense, nocheidal turf. Usually the roots account for the main mass of the cereal, sometimes up to 90%. Such a root system, effectively absorbing and accumulating water, helps to survive in the conditions of regular blending animals, periodic droughts and steppe fires.

Flowers.

Flowers are small, minor, without a clearly pronounced perianth. Petals and sewers are represented by one or more miniature flakes, which are called flowering films, or locked, and are located under the stamens. The flower is usually scaretable, i.e. Contains both stamens and pestle. The pestle consists of a wound with two (less often - three) bars carrying long cigarettes. The stamens are usually three - with long breathing with threads and oblong anthers.

These parts are surrounded by scratch-shaped bracts, i.e. Small, highly modified leaves. Usually, among them, the upper, narrower, flower scales and lower flower scales are isolated, which is larger and sometimes wars the top. Reproductive parts, Lodikulas and these scales form a compact structure, called Flower from cereals. Flowers with two opposite rows are located on the thin axis of the spikelet, at the base of which there are two modified binding sheet of inflorescences - spikey scales. They, like the bottom flower scales, are on top of being pointed or stretched into sustain, sometimes very long. Flowers on a spikel axis with spikey scales form a compact inflorescence - spikelet. Deviations are possible from this general scheme: Some species of spikelets are single-flowered, from the spiked scales there are only one or they are missing at all, etc.

Spikelets, in turn, are attached to a larger axis of complex inflorescences. If this axis is simple, the inflorescence is called a brush (spikelets on short legs) or spikes (spikelets sitting). However, most cereals have the main axis of inflorescence branching and spikelets are on its side branches. Such a complex brush is called panic.

Fetus.

Wrinkle in cereals one-minor, i.e. It contains the only cavity with a seed. After pollination and fertilization of the egg in the seedness, the latter ripens in a seed with an embryo containing nutrients with endosperm and seed peel, which grows with the wall of the ovary (by the ossampite); So the characteristic creek fruit is formed, called the grain or in use is simply grain, such as wheat, corn, etc. It differs from the fruits of another type, it is very thin by the ocoloblodnik, almost inseparable from the only seed.

Grand-like plants: Source and Sitnikov.

For raw hasshes are characterized by two plants families - Source (Cyperaceae) and Sitnik (Juncaceae), which are often confused with cereals due to external similarities.

However, the deadlines differ from cereals with several well-pronounced signs. The stem of cereals is nodal, in the interstils are usually hollow and in cross section round. Oskock he without knots, usually incomplete and in a triangular section. Sheet vagina in cereals, as a rule, without struggling with edges and easily separated from the stem; Sourced - closed, its very firmly embracing. The focus of the cereals is a two-round, three-row. Flowers have sediments, like cereals, devoid of the perianth and are collected in spikelets, but each flower is protected by two, like cereals, but one bract, and spikelets often form an umbrella inflorescence, i.e. There are on the ends of the legs overlooking one point on the top of the stem. Finally, the fruit in the dies - nuts or seeds: his octoper does not grow up with the only seed.

Sitnik sitter stems without knots, incomplete, round in cross section. The leaves usually depart only from their base. The vagina is unlocked, but there is no tongue, and the sheet plate is cylindrical. Flowers are small and unbroken, but with six identical scratch-shaped elements of the perianth, located three in two circles. Inflorescences in principle cinema, i.e. The first flower is revealed on the top of the central axis, and then the rest - on the branches extending below, however, it may look like metels, brushes, and the like. The fruit is not a grain and not a seed, but a three-day or one-minute box with small seeds, revealed and dissipating them in maturation.

To the family of dies other than the Oskock refers to the reed (genus Scirpus.). This word is often incorrectly called the types of rogozes from a completely different family (Typhaceae). Of the economically important, at least in antiquity, the papyrus deserves dwelling ( Cyperus Papyrus.).

The role and use of cereals.

Since the oldest times, the cereals were the basis of the nutrition of people and livestock. In the United States, only corn is produced for about $ 18 billion. An essential part of agricultural land in this country is occupied by pastures with feed cereals or grassresses (mixed crops of cereals and legumes), which give more than a third of the necessary cattle. About the importance of corn and other food cruise, such as Oats, millet, wheat, rice, rye, sorghum, cm. Relevant articles.

Bamboo is widely used in construction. Its rustic stems reach a height of more than 30 m with diameter at the base of 20-25 cm. Of these, not only build houses, bridges and hedges, but also make mats, vessels, decorative items. In the old days they were also needed for the manufacture of copies and arrows.

Fighting erosion.

Erosion and decrease in soil fertility global problems. Grass helps to solve it. For example, in the US, they along with other seaside herbs are used to fix the sand dunes. At these cereals are usually long rhizomes (underground stems) and rigid elastic leaves, withstanding impacts of sand-raised sand.