Grasses

Grasses, a large group of monocotyledonous plants constituting the natural order Grantineae, and comprising about 4,500 species in about 250 genera. The term is popularly used for many green herbaceous plants which are not members of this order, the limits of which were first suggested by the classification of Linnaeus (q.v.), in which most true grasses appear under the order Digynia of the class Triandria, having two styles and three stamens.

Grasses occur in all climates, those of temperate regions being generally herbaceous and "social," ie. growing together in great numbers and considerable variety, and so forming "pastures," whilst in warmer countries they are often in tufts or arborescent, some bamboos (q.v.) having, 50 or 60, or even upwards of 100 stems. The roots are fibrous and the stems generally cylindric, with swollen nodes and hollow and elongated internodes, though the sugar-cane (q.v.) has short and solid internodes. The perennial forms have commonly creeping rhizomes, with solid internodes, from which the erect aerial branches or culms (q.v.), often themselves branched, grow with great rapidity, a bamboo even reaching 100 feet in two months. The culm secretes a large amount of silica in its epidermal cells, and becomes hard and polished externally. The leaves are distichous, have a long sheath forming a generally split tube embracing the internode, seldom with any petiole, but with a membranous outgrowth, or ligule, at the base of the long, narrow, linear, tapering blade. The flowers are very variously grouped in racemes or panicles of small spikes, or spilcelets, and are generally bi-sexual, though maize and some of the arborescent forms are monoecious. Each spikelet has generally two empty glumes (q.v.) at its base, and may contain one, two, or many flowers besides other empty glumes or "barren flowers." Below each flower there are usually two glumes at different levels, belonging, in fact, to distinct axes. The lower of these, the flowering glume, is often furnished with an awn (q.v.) either at its apex or springing from it dorsally, which represents the blade of a leaf. The upper glume or pale is membranous, and has two lateral veins and no midrib, representing two united bracteoles. It is close below the flower. The outer perianth-whorl is almost always suppressed, and the inner one represented by two minute hypogynous scales known as lodicules. There are three of them in bamboos, and six in Strepiochcete. There are usually three stamens alternating with the lodicules, and belonging, therefore, to an outer whorl; but in rice (q.v.) and most bamboos there are six, in two whorls, and sometimes more, or only two or even one. They are commonly exserted, with long weak filaments and pendulous versatile anthers with lobes diverging at each end. The gyneeceum consists typically of two carpels united into a one-chambered ovary with two distinct styles and feathery stigmas, the flowers being commonly wind-pollinated. In a few cases there is only one style, which in maize (q.v.) reaches a length of six inches, and in some bamboos there are three. In all cases there is but one ovule, which generally entirely fills the ovary. The fruit or caryopsis is commonly deeply grooved down the line of junction of its carpels and is very rarely fleshy. In Coix lachryma it is enclosed by a strong white polished bract or involucre, whence it has the name of "Job's tears." The seed is mainly filled with mealy endosperm, the embryo lying at one side of its base.

The value of grasses depends primarily on their farinaceous fruit or "cereal grains," the chief bread-stuffs and staple food of the world; secondly, on the use of their herbage, either green or as hay for fodder for cattle; thirdly, on the sugar of their sap. The chief cereals, wheat, rice, maize, barley, oats, rye, and millet, are dealt with in separate articles (q.v.). Among the chief fodder-grasses are rye-grass (Lolium), Timothy-grass (Phleum), Cynnsurus and Anthoxanthum; and the tussac grass, Festuea ftabelloides of the Falkland Islands

Besides the sugar-cane (q.v.), sugar is obtained from various species of Sorghum. The Espartograss, Macrochloa tenacissima, and Alfalfa, Lygeum spartum, are both used as paper materials, as also is the straw of the cereals and the bamboos, whilst the latter group have endless uses as a light strong timber. Finally the fragrant oils of geranium, ginger-grass, obtained from East Indian species of Andropogon, must be mentioned. '