cristalus, Linn. Crested Dog's tail. (Fig. 545.) A perennial grass, one to two feet high, with fine and chiefly radical leaves. Occasionally sown in grass mix tures but without much forage value.
24. Poa (Greek, for fodder). A genus of about 125 species of grasses, chiefly in the cooler regions of both hemispheres. Spikelets two- to six-flow ered, the uppermost flower more or less imperfect ; glumes one- to three-nerved, keeled ; lemma keeled, five-nerved, awnless. Inflorescence a more or less spreading panicle. Annuals or perennials.
arachnifera, Torr. Texas Blue-grass. (Fig. 546.) A dicecious perennial grass with running rootstocks. The staminate and pistillate panicles are distinctly different in appearance, owing to the fact that the lemmas of the staminate spikelets are smooth while those of the pistillate spikelets are densely long woolly, which character at once distinguishes this species.
eompressa, Linn. Canada Blue-grass. (Fig. 547.) A perennial with scattered, flattened stems, six to twenty inches high, from creeping rootstocks which form a strong turf. Panicle comparatively small and narrow. Because of the characteristic shape of the stem it is called fiat-stem in the middle Alle ghany region. In New England and in some other localities it is known as blue-grass, but this name should be restricted to Poa pratessis. It is also sometimes called wire - grass. The foliage has a peculiar blue- green color. It is a native of Europe and of the northern part of America.
nemoralis, Linn. Wood Meadow-grass. (Fig. 548). A tall perennial (one to three feet) with open spread ing panicle, four to six inches long ; spikelets mostly two- to three-flowered, lemma webby at base, keel and marginal nerves pubescent, intermediate nerves glabrous and obscure ; ligule very short.
This European species is occa sionally cultivated as a meadow grass or in mixtures, and has escaped in the northeastern states. It is adapted to shaded situations. Probably not na tive.
pratensis, Linn. Kentucky Blue-grass. (Figs. 549-551.) A perennial grass growing in tufts, but producing abundant rootstocks by which it soon forms a firm sod. Panicles spreading but not dif fuse, two to five inches long. Spikelets mostly three- to five-flowered ; lemma much as in the pre ceding, but the intermediate nerves more promi nent. A valuable grass, native in the northern
part of both hemispheres and widely cultivated for pasture and lawns. It does not thrive in the South.
tr trlora Gelib. (P. serotina, Ehrh.). Fowl Meadow grass. (Fig. 552.) This grass closely resembles P. moralis. It usually grows taller and has a larger panicle. Probably the best character to distinguish between the two is the ligule, which in triflora is about three millimeters (one - eighth inch) long, while in nemoralis it is scarcely measurable. This species is native in the northern part of America as well as in Europe. It has been incorrectly re ferred to P. flare, Linn. Sometimes known as false red-top.
tririalis, Linn. Rough-stalked Meadow-grass. (Fig. 553.) In general appearance much resembling P. pratensis, but usually with a larger and more spreading panicle. It differs in the absence of well developed rootstocks, in the sheaths rough to the touch (hence the common name), and in the glabrous marginal nerves of the lemma. Occasionally grown in mixtures for meadows. A native of Europe but escaped from cultivation in the northeastern states. It is adapted to shaded situations.
25. Festuca (Latin, straw). A genus of about eighty species of mostly perennial grasses, scat tered over all parts of the globe but chiefly in tem perate regions. Spikelets several-flowered, glumes narrow and acute ; lemmas rounded on the back, or keeled at apex, often awned from the tip, faintly three- to five-nerved, rather hard in texture. In florescence from a narrow raceme to a spreading panicle.
clatior, Linn. Tall Fescue. A tall grass (three to four feet) with large flat leaves, large but rather narrow panicle and large, five- to ten - flowered, awnless spikelets (about one-half inch long). Native of Europe and cultivated for forage. Frequently escaped from cultivation. A smaller form (var. pratensis, Gray (Fig. 554); E. pratensis, Huds.), with narrower panicle of fewer spikelets, is more com monly cultivated under the name of meadow fescue, and is a more valuable agricultural grass. Some times called Randall grass. The tall fescue makes a ranker growth than the meadow fescue.