The graminaceous Poacées or (scientific name Poaceae or Gramineae ) form important a botanical Famille. They draw their current name from the kind Poa (the Pâturin S).
One gathers there nearly 12.000 species in addition to 700 kinds and one finds there the majority of the species of plants which one commonly calls “Herbe S”, but not only, the Bambou S for example are also of Poacées, the only ones to have lignified stems .
It is a cosmopolitan family which presents a major economic interest, ensuring most of the food of humanity.
Morphology
They are herbaceous , annual or long-lived plants in general with hollow Tige cylindrical carrying nodes, the Chaume, generally not ramified except on the level of the ground where often the phénomème Tallage occurs, which leads to the formation of characteristic tufts. Certain species produce rhizomes and let us stolons which allow the occupation of the ground on the surface and the formation of Pelouse S.
The roots form hairy important, in particular thanks to the formation of many adventitious roots being born with the base from the stems.
The narrow sheets, to parallel veins, stick on the stems by a split sheath showing to the junction with the limb a line of hairs or a strip called Ligule.
The Inflorescence S are made of épillet S. When those stick directly on the stem, one obtains a ear (corn, Chiendent) if not when they are pedicels, the inflorescence is a Panicule (oats, Agrostis, reeds).
The fruit is called a Caryopse.
Surface of distribution
The graminaceous ones are one of the families more Cosmopolite S. One finds them on all the continents (except for the covered Antarctic of ice) from the equatorial zones to the polar circles and since the seaside until the top of the mountains.This family of “sociable” plants very accounts for approximately 20% of the vegetable cover of the terrestrial sphere. They are the element dominating several very wide vegetable formations like the Steppe, the Savane, the Pampa, the Grandes American plains and the alpine Pelouse. They allowed the development of a whole fauna Herbivore.
Economic importance
Among Poacées, one finds species essential in the world economy, and of which the use is vital for the food of the man and of sound Bétail:
- the Cane with sugar, first world culture by the importance of collected tonnages (1,3 billion tons) and first source of Sugar;
- the Cereal S cultivated: Corn, Rice, Corn, Barley, oats, Rye, millet, etc, which occupy half of the total of the arable lands and produce 2 billion tons annually; the cereals provide also raw materials for industry (derivatives of the Amidon, alcoholic Fermentation …),
- of many fodder plants like the dactyl, the Fescue, the Rye-grass, the brominates, etc, cultivated in meadow S permanent or temporary, and the Sorgho, transformed mainly into Ensilage;
- of the plants exploited for their Fiber S like the Esparto, (paper pulp) and the Sparte;
- of the plants of varied use, like the Bamboo S and the canes of Provence or the Oyat (fixing of the dunes);
- plants used for approval: graminaceous for Grass S, sports grounds, etc, and the vegetalisation of the slopes of roads and railways;
Principal kinds
- See the complete listing of the kinds
See too
Related articles
- Graminaceous decorative
External references
External bonds
- See a detailed diagram of the Graminaceous ones.
- Some Poacées savages icaunaises.
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