Spikelets 1-flowered, terete; the flower falling away at maturity (with the conspicuous obconical bearded and often sharp-pointed callus) from the membranaceous persistent lower glumes. Fertile glumes coriaceous, cylindrical-involute and closely embracing the smaller palet and the cylindrical grain, having a long and twisted or tortuous simple awn jointed with its apex. Stamens mostly 3. Stigmas plumose.—Perennials, with narrow involute leaves and a loose panicle. (Name from στύπη, tow, in allusion to the flaxen appearance of the feathery awns of the original species. In our species the awn is naked.)
[*] Callus or base of the flower short and blunt; lower glumes pointless.
1. S. Richardsònii, Link. Culm (1½–2° high) and leaves slender; panicle loose (4–5´ long), with slender few-flowered branches; lower glumes nearly equal, oblong, acutish (2½–4´´ long), about equalling the pubescent linear-oblong fertile one, which bears a tortuous awn 6–9´´ long.—Pleasant Mountain, near Sebago Lake, Maine, Mt. Marcy, N. Y., north shore of L. Superior, Mont., and northward.
[*][*] Callus pungently pointed, at maturity villous-bearded; flowering glume slender and minutely bearded at the tip; empty glumes taper-pointed.
2. S. avenàcea, L. (Black Oat-Grass.) ([Pl. 8.]) Culm slender (1–2° high); leaves almost bristle-form; panicle open; fertile glume blackish, nearly as long as the lower ones (about 4´´ long); the awn bent above, twisted below (2–3´ long).—Dry woods, S. New Eng. to Wisc., and southward.
3. S. spàrtea, Trin. (Porcupine Grass.) Culm rather stout (1½–3° high); panicle contracted; fertile glume linear, ¾–1´ long (including the long callus), pubescent below, shorter than the lanceolate slender subulate pointed greenish lower glumes; the twisted strong awn (3½–7´ long), pubescent below, rough above.—Plains and prairies, from Ill. and N. Mich. northwestward.
4. S. virídula, Trin. Culms clustered, 1–3° high or more; panicle narrow and usually dense, 6–18´ long; glumes very thin, 3–4´´ long; fertile glume usually somewhat silky, with a short callus; awn 1´ long, slender, glabrous or a little pubescent below.—W. Minn., Dak., and southwestward.
21. ORYZÓPSIS, Michx. Mountain Rice. ([Pl. 8.])
Spikelets 1-flowered, nearly terete. Lower glumes herbaceous or thin-membranaceous, several-nerved, nearly equal, commonly rather longer than the oblong flower, which is deciduous at maturity, and with a very short obtuse callus or scar-like base. Flowering glume coriaceous, at length involute so as closely to enclose the equal palet and the oblong grain; a simple untwisted and deciduous awn jointed on its apex. Stamens 3. Squamulæ 2 or 3, conspicuous. Stigmas plumose.—Perennials, with rigid leaves and a narrow raceme or panicle. Spikelets greenish, rather large. (Name composed of ὄρυζα, rice, and ὄψις, likeness, from a fancied resemblance to that grain.)
[*] Styles distinct, short; culm leafy to the summit; leaves broad and flat.