GRASSES (Graminew). A natural order of plants, which contains more than 300 genera and 35b0 species. Its members vary in size from moss like specimens less than an inch in height to gigantic bamboos 100 feet or more tall. They are distributed over nearly the whole world; some are characteristic of the hottest tropical regions, others of the far north and south, in the vicinity of almost perpetual snows. In number of specimens they are most abundant in the north temperate zone, where they clothe with verdure immense tracts of prairie. meadow, and steppe, and may he found growing or may be made to grow on almost every kind of soil. Some species are peculiar to dry, sterile soils; others will flourish only in rich soils with abundant moisture. Some grow in marshes, stagnant water, or slow streams, and others only along the seacoast. None are truly marine. Some are annual, others perennial. The roots of all grasses are fibrous. Many have more or less thickened underground rootstocks or rhizomes, which are not true roots; but modified stems, from which roots are sent out and from which new plants may arise under conditions favorable to propagation. The stems, which usually branch more or less at their bases, are round Q r slightly flattened, jointed, and hollow between the joints except in maize, sorghum, and a few other species. The parts of the stem between the joints, or nodes, are called the internodes. The stem elongates by growth at the base' f the inter nodes. From the nodes, or joints, arise the leaves and branches. In some grasses roots are put out from the joints when near or lying upon the ground. If a stem is bent or broken so as to lie upon the ground, growth at once begins in the lower side of the stem and is rapidly con tinued until the stem again assumes an upright position. In most grasses the stems are her baceous; in the bamboos and some other species they are woody. The leaves consist of two parts, the sheath and the blade. The sheath, which, is split on the opposite side from the blade, invests the stem and protects the lower growing portion of the internode. At the top of the sheath is usually found a thin membranous prolongation, called the ligule. The leaf-blade is usually long and narrow, with nearly parallel longitudinal veins.
Many grasses are provided with peculiar adap tations to protect them against drought and hot winds. Between the veins on one side or the
other are large, thin-walled cells that keep the leaf expanded when normal conditions are present. When dried by hot winds they collapse and cause the leaf to roll its margins inward, thus protect ing it against too great evaporation. When rain comes the cells swell out and cause the leaf to return to its normal shape. The position of the leaves upon the stem grasses is opposite and two-ranked, a character by which grasses may be distinguished from sedges, which have three ranked leaves. Lawn and meadow grasses have leaves that grow constantly from their bases, so that when cut they quickly elongate, instead of remaining in the shorn condition. Grass-flowers possess only the essential organs, i.e. stamens and pistils; the scales and bracts surrounding them are reduced and modified leaves. The flowers of some grasses have both stamens and pistils; others have the staminate and pistillate flowers upon different parts of the plant, as in the case of maize, in which the tassel consists of staminate flowers and the silk of the ears of the pistillate flowers. Still others have them upon different individuals. The usual number of stamens in the flower is three, but the number varies from one to six, and in some genera they may be from 20 to 30. The anthers, which are usually con spicuous, are generally attached by the middle of their backs to the slender filaments, so that they sway in the winds. The pistils consist of the ovary and usually two plumose stigmas, which may be sessile or raised upon styles. The ovary contains a single ovule, which ripens with the ovary wall, or pericarp, into a true caryopsis. The flowers are arranged in spikelets, which con tain one or more flowers. At the base of each flower is a bract, ar reduced leaf, called the flowering Blume, and at the base of each spikelet are commonly found two empty glumes. The axis or stem that carries the glumes is called the rachilla. Between the rachilla and the indi vidual flower there is a small, nerved, membra naceous bract called the pales or palet. The glumes, which vary exceedingly in different species, may have awns (bristle-like appendages, as the 'beard' of wheat) or may be sharp-pointed or rounded, entire or toothed at their apexes.