1. CYPÈRUS, Tourn. Galingale. ([Pl. 1.])
Spikelets many–few-flowered, mostly flat, variously arranged, mostly in clusters or heads, which are commonly disposed in a simple or compound terminal umbel. Scales 2-ranked, conduplicate and keeled (their decurrent base below often forming margins or wings to the hollow of the joint of the axis next below), deciduous when old. Stamens 1–3. No bristles or inner scales. Style 2–3-cleft, deciduous. Achene lenticular or triangular, naked at the apex.—Culms mostly triangular, simple, leafy at base, and with one or more leaves at the summit, forming an involucre to the umbel or head. Peduncles or rays unequal, sheathed at base. All flowering in late summer or autumn. (Κύπειρος, the ancient name.)
§ 1. PYCRÈUS. Achene lenticular, the edge turned to the rhachis; spikelet flattened, many flowered; rhachis narrow, not winged. Annuals.
[*] Umbel simple or capitate, rarely slightly compound.
1. C. flavéscens, L. Culms 4–10´ high, spikelets 5–8´´ long; involucre 3-leaved, very unequal; spikelets becoming linear, obtuse, clustered on the 2–4 very short rays (peduncles); scales obtuse, straw-yellow; stamens 3; achene shining, orbicular, its superficial cells oblong.—Low grounds, N. Eng. to Mich., Ill., and southward. (Eu., etc.)
2. C. diándrus, Torr. (Pl. 1, fig. 1–4.) Spikelets lance-oblong (3–9´´), scattered or clustered on the 2–5 very short or unequal rays; scales rather obtuse, purple-brown on the margins or nearly all over; stamens 2, or sometimes 3; achene dull, oblong-obovate; otherwise much like the last.—Low grounds, common from the Atlantic to Minn., Ark., and N. Mex.—Var. castàneus, Torr. Scales more firm and browner; with the type.
3. C. Nuttàllii, Torr. Culms 4–12´ high; spikelets lance-linear, acute and very flat (½–1´ long), crowded on the few usually very short (or some of them distinct) rays; scales oblong, yellowish-brown, rather loose; stamens 2; achene oblong-obovate, very blunt, dull.—Mostly in salt or brackish marshes, along the coast from Mass. to the Gulf.
4. C. polystàchyus, Rottb., var. leptostàchyus, Boeckl. Culms very slender, 6–15´ high; leaves and elongated involucre very narrow; spikelets few to many on the 4–8 rays, linear, acute, 2–9´´ long; scales thin, ovate, acute, closely imbricated, pale brown; stamens 2; achene linear-oblong or clavate, short-pointed, grayish and minutely pitted. (C. microdontus, Torr.)—Margins of ponds and streams, Va. to Fla. and Tex.
[*][*] Umbel compound.
5. C. flavícomus, Vahl. Culm stout (1–3° high); leaves of the involucre 3–5, very long; spikelets linear (4–9´´ long), spiked and crowded on the whole length of the branches of the several-rayed umbel, spreading; scales oval, very obtuse, yellowish and brownish, broadly scarious- (whitish-) margined; stamens 3; achene obovate, mucronate, blackish.—Low grounds, Va. to Fla.