This section is from the book "An Illustrated Flora Of The Northern United States, Canada And The British Possessions Vol1", by Nathaniel Lord Britton, Addison Brown. Also available from Amazon: An Illustrated Flora of the Northern United States, Canada and the British Possessions. 3 Volume Set..
Strongly resembling C. atlantica, but more slender, the culms acutely triangular and roughened above, 10'-24' tall. Leaves usually less than 1" wide, not stiff, flat or in drying involute, usually exceeding the spikes, the lower less conspicuously shortened; spikes 3-4, spreading, subglobose, 2 1/2"-3' in diameter, 6-20-flowered, the staminate flowers numerous at base of terminal one; perigynia brownish at maturity, with suborbicular body, planoconvex, \\" long, about 1" wide, sharp-margined, rounded at base, rather lightly nerved on both faces, spreading or reflexed at maturity, abruptly tipped with a stout, rough, 2-toothed beak, not half as long as the body; scales acute to short-acuminate; stigmas 2.
In boggy places, Massachusetts to Michigan, Pennsylvania and Florida. May-July.
Similar to C. Leersii but stouter, culms obtusely triangular below, more sharply triangular and roughish above, 1°-2 1/21/2° tall. Leaves 1"-2" wide, stiff, flat or in drying somewhat involute, the upper sometimes overtopping the spikes, the lower very short and acute; spikes 3-7, spreading, subglobose or short-cylindric, nearly 3" in diameter, 15-50-flowered, the staminate flowers numerous at the base of the terminal one, or this rarely entirely staminate; perigynia green, with suborbicular body, plano-convex, sharp-margined,1 1/2"-1 3/4" long, 1"-1 1/2" wide, rounded at the base, strongly nerved on both faces, spreading or reflexed at maturity, abruptly tipped with a stout, rough 2-toothed beak less than half as long as the body, the margins sometimes incurved; scales acutish to acute, shorter than the perigynia.
In swamps, near the coast, Newfoundland to Florida and Texas. Also very rarely inland in Quebec, Maine, New York and Pennsylvania, according to Fernald. June-July.
C. rosaeoides E. C. Howe; Gord. & Howe, Fl. Renssalaer
Co. 33. 1894. C. seorsa E. C. Howe; Gord. & Howe, loc. cit. 39. 1894.
Culms caespitose, slender, weak, flattened, often spreading or reclining, 7'-2o' tall, roughened on angles. Leaves l"-2" wide, shorter than the culm; bracts very short, or lowest occasionally developed; spikes 3-7, the lateral usually pistillate, with 5-20 spreading perigynia, subglobose or short-oblong, more or less separate, 2"-3 1/2" long, 2"-3" wide, the terminal gynaecandrous, or sometimes entirely staminate, much longer and long-clavate at base; perigynia green, plano-convex, ovoid-oval, broadest near middle, 1 1/4" long, 3/4" wide, several-nerved on both faces, spongy and round-tapering at base, abruptly narrowed into the smooth beak 1/4- 1/3 length of body, its teeth short, erect; scales ovate, hyaline, shorter than perigynia; achene in upper part of perigynium.
In swampy woodlands, Massachusetts to New York, south to Stone mountain, Georgia. May-June.