Page:The New International Encyclopædia 1st ed. v. 09.djvu/170

* GRASSES. 146 GRASSES. the seacoast. None are truly marine. Some are annual, others perennial. The roots of all grasses are fibrous. jMany have more or less thickened xinderground rootstoeks 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 gr slightly llattened, jointed, and hollow between the joints except in maize, sorghum, and a few other species. The parts of the stem hetween the joints, or nodes, are called the internodes. _ The stem elongates hy growth at the base of 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 arei 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 intemode. At the top of the sheatli 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 in grasses is opposite and two-ranked, a character by which grasses may 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 diff'erent parts of the plant, as in the ease of maize, in which the tas.sel consists of staminate flowers and the silk of the ears of the pistillate flowers. Still others have them upon difl'erent 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 Oi' the' ovary and usually two plumose stigmas, ' PAMPAS GRASS. be distinguished from sedges, which have three- ranked leaves. Lawn and meadow grasses have leaves that grow constantly from their bases, so that when ciit they quickly elongate, instead of remaining in the shorn condition. Grass-flowers possess only the essential organs, i.e. stamens and BOFFALO GRASS. which may be sessile or raised upon styles. The ovary contains a single ovule, which ripens with the ovarj' 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, or reduced leaf, called the flowering glume, and at the base of each spikelet are commonly found two empty glumes. The axis or stem that can'ies the glumes is called the rachilla. Between the rachilla and the indi- vidual flower there is a small, nen-ed, membra- naceous bract called the palea or palet. The glumes, which vary exceedingly in diff'erent species, may have awns (bristle-like appendages, as the Tjeard' of wheat) or may be sharp-pointed or rounded, entire or toothed at their apexes. All of these characters are of importance in determining the species of grasses. The arrange- ment of the spikelets in the head, as it is often improperly called, is varied. They may be sessile along the axis, as in wheat, forming a spike; they may all be arranged on one side of the axis or ra- chis, forming a raceme, or the rachis may branch videly into a panicle, as in oats, blue grass, etc., and there are many intermediate forms between these. According to their most common uses grasses may be divided into lawn, pasture, and hay grasses. Among the more common grasses suited to laais are blue grass, Rhode Island bent grass redtop. Bermuda grass. Saint Augustine grass, and buff'alo grass. Pasture grasses in- clude : Redtop, blue grass, bent grass, fescue, orchard grass, bronie grass, Bermuda grass, grama grass, rye-grass, blue-stem, and mesquit. Hay grasses include: Timothy, orchard grass, red- top, blue grass, hrome grass. Johnson grass, tall oat-grass, meadow fescue, meadow foxtail, rye- grass. Guinea grass, crab-grass, crested dog's tail, etc. In addition many grasses are especially
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