[*] 4.—[+] 4. Débiles.
[++] Perigynium thin, rarely with more than two prominent nerves.
51. C. arctàta, Boott. Slender, erect, 1–2° high; radical leaves much shorter than the culm and very broad (2½–5´´), flat; bracts broad and short, long-sheathing; spikes 3–5, all widely spreading or drooping on filiform stalks, 1–3´ long and exceedingly slender; perigynium short (2´´ long or less), abruptly and conspicuously stipitate and abruptly contracted into a beak, 3-cornered, prominently nerved, green, mostly spreading, scarcely longer than the very sharp or cuspidate scale.—Woods and copses, N. Eng. to Penn. and Minn.; common.
Var. Faxòni, Bailey. Spikes shorter and usually short-peduncled, erect or nearly so, much more densely flowered, part of them commonly contiguous at the top of the culm, rendering the shorter staminate spike inconspicuous; perigynium usually larger.—Lisbon, N. H. (Faxon); Keweenaw Co., Mich. (Farwell); extreme northern Minn. (Bailey); also in Canada.
52. C. débilis, Michx., var. Rúdgei, Bailey. Very slender and diffuse, 1–2½° high (or rarely reduced to 3–4´!); leaves narrow and lax, longer than the culm; spikes mostly heavier than in the last; perigynium much longer, very gradually narrowed at each end, scarcely angled and not prominently nerved, rusty when ripe, erect, twice longer than the obtuse or acutish scale. (C. debilis, of last ed.)—Copses, N. Eng. to N. Mich., and southward; frequent east and southward.—Var stríctior, Bailey. Usually taller, strict; leaves broader (about 2´´ wide) and firmer; spikes stiffer, simply spreading or even erect; perigynium mostly shorter and greener, often little exceeding the scale. White Mts. (Faxon).—Var pùbera, Gray. Perigynium usually more slender, more nerved and minutely pubescent. Center and Lancaster Counties, Penn. (Porter, Lumsden), and Bedford Co., Va. (Curtiss).
C. débilis × viréscens, Bailey. Plant slender and very green; leaves flat, rough, mostly longer than the culm, spikes 2–3, 2´ long, thin and slender, erect or nearly so, the terminal one bearing a few pistillate flowers at top; perigynium exactly intermediate between the two species, lance-ovate, nerved and slightly hairy, short-beaked, thin, twice longer than the scale.—Revere, near Boston, Mass. (Faxon).
[++][++] Perigynium firm, prominently many-nerved.
53. C. venústa, Dewey, var. mìnor, Boeckl. Slender but strict, 1½–2° high; leaves narrow and strict, about as long as the culm; spikes 1–2´ long, scattered, the upper usually ascending, the terminal one sometimes staminate at top; perigynium ascending, the very short and stout beak prominently toothed, thrice longer than the rusty narrow scale. (C. glabra, Boott.)—Sphagnous swamps, Oneida Co., N. Y., N. J., and southward; local.
[*] 4.—[+] 5. Gracíllimæ.
[++] Perigynium small, scarcely turgid.