C. fúscus, L. Of similar habit; spikelets much smaller (2–4´´ long), the thin brown scales (greenish only on the keel) barely acutish and very faintly nerved.—Revere Beach, Mass. (Young); on ballast at Philadelphia. (Adv. from Eu.)
[+][+] Perennial, propagating from hard clustered corms or bulb-like tubers.
10. C. Schweinítzii, Torr. Culm rough on the angles (1–2° high); umbel 4–8-rayed, rays very unequal, erect; spikelets loosely or somewhat remotely 6–12-flowered, with convex many-nerved scales; joints narrowly winged.—Dry sandy shores and ridges, western N. Y. and Penn. to Minn. and Kan.
11. C. filicúlmis, Vahl. Culm slender, wiry, often reclined (8–15´ high); leaves linear (½–2´´ wide) or filiform; spikelets numerous and clustered in one sessile dense head, or in 1–7 additional looser heads on spreading rays of an irregular umbel; joints of the axis naked; scales blunt, greenish.—Dry sterile soil; common, especially southward.
12. C. Gràyii, Torr. Culm thread-form, wiry (6–12´ high); leaves almost bristle-shaped, channelled; umbel simple, 4–6-rayed; spikes 5–10 in a loose head, spreading; joints of the axis winged; scales rather obtuse, greenish-chestnut-color.—Barren sands, Plymouth, Mass., to N. J., near the coast.
§ 3. PAPỲRUS. Style 3-cleft; achene triangular; stamens 3; spikelets many-flowered, flattened, the carinate scales decurrent upon the rhachis as scarious wings; spikes in simple or compound umbels.
[*] Wings of the rhachis soon separating to the base as a pair of free scales; annual.
13. C. erythrorhìzos, Muhl. (Pl. 1, fig. 5–8.) Culm obtusely triangular (3´–3° high); umbel many-rayed; involucre 4–5-leaved, very long; involucels bristle-form; spikelets very numerous, crowded in oblong or cylindrical nearly sessile heads or spikes, spreading horizontally, linear, flattish (3–6´´ long), bright chestnut-colored; scales lanceolate, mucronulate.—Alluvial banks, L. I. to Penn., Mich., Minn., and southward; also adventive in N. Eng.
[*][*] Wings of the rhachis persistently attached; perennial by slender running rootstocks.
[+] Achene round-obovate; scales mucronate or acute, free or spreading.