26. C. Houghtònii, Torr. Stiff, 1–2° high, extensively creeping; culm rather sharply angled, rough, exceeding the leaves; leaves flat and very sharp-pointed; spikes 1–3, sessile or the lowest short-stalked, erect, varying from nearly globular to cylindric (1½´ long), compact; perigynium short-ovate, stiffly pubescent, prominently nerved and toothed; scale thin-margined, acute or awned, shorter than the perigynium.—Sandy knolls and banks from Maine to Minn. along our northern borders, and northwestward; rather local.
27. C. filifórmis, L. Tall and very slender but erect, 2–3° high; culm obtuse, smooth; leaves very long, involute-filiform, rough; spikes 1–3, sessile, somewhat scattered, erect, short and thick (rarely over 1´ long); perigynium very short-ovate, the teeth very short, the few nerves obscured by the dense stiff hairs; scale thin and blunt, about as long as the perigynium.—Bogs, throughout, north of Penn.; frequent. (Eu.)
Var. latifòlia, Boeckl. Culm mostly rough above; leaves flat, 1–2´´ broad; spikes usually somewhat slimmer and scales often sharper and longer. (C. lanuginosa, Michx.)—Swales and low meadows, throughout; common.
C. hírta, L. Variable in size (½–2° high), widely creeping; culm rather slender but erect, obtuse and smooth or slightly rough above; leaves soft and flat, generally sparsely hairy and the sheaths very hirsute, rarely smooth; spikes 2–3, distant, more or less shortly-peduncled, erect or nearly so, 1½´ long or less and rather loose; perigynium long-ovate, nerved, soft-hairy, the prominent beak slenderly toothed; scale thin and green-nerved, awned, mostly a little shorter.—E. Mass. to central N. Y. and Penn. (Nat. from Eu.)
[*] 2.—[+] 4. Paludòsæ.
[++] Teeth slender, mostly spreading.
28. C. trichocárpa, Muhl. Stout and tall, 2–3° high; culm sharply angled, rough above; leaves very numerous, flat and very rough, but not hairy, much exceeding the culm; spikes 2–5, scattered, the lower stalked and more or less spreading, long and heavy (1–4´) but loosely flowered at base; perigynium long-ovate, many-costate, sparsely short-hairy, about twice as long as the membranaceous, acute or acuminate scale.—Marshes; frequent.—Var. imbérbis, Gray. Mostly smaller throughout; perigynium smooth; scales usually sharper and longer. Drier places, N. Y. to Mo.; infrequent.
Var. Dewèyi, Bailey. Leaves narrower, often becoming somewhat involute, smoother; spikes short (seldom over 1½´ long), all but the lowest one sessile; perigynium smooth, thick in texture, becoming polished with age, the nerves impressed; scales sharp, mostly a little shorter than the perigynium.—Dakota (Seymour), and northwestward. Resembles small forms of n. 29.
Var. aristàta, Bailey. Mostly stouter; leaves more or less hairy on the under surface and sheaths; perigynium usually longer, smooth, the teeth longer and more spreading. (C. aristata, R. Br.)—N. Eng. to Minn.; rare eastward.
[++][++] Teeth short, erect or very nearly so.