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..
Culms elongated, the old ones prostrate, sending up from apical nodes (usually) fertile culms and from lower nodes sterile culms, the latter in succeeding seasons becoming prostrate and sending forth new culms from the nodes, the roots little developed. Fertile culms erect, smooth, 4'-18' tall; leaves 1"- 1 1/2" wide, shorter than the culm, somewhat involute in drying, straight, the lower ones reduced to short sheaths; spikes 2-4, bractless, androgynous, aggregated into a terminal ovoid or oblong head 3"-6" long; perigynia broadly ovoid, \" long, 1" wide, flat on the inner side, convex on the outer, very thick, strongly many-nerved, slightly margined, abruptly tipped by a very short entire beak; scales ovate or ovate-lanceolate, brown, acute or acuminate, equalling the perigynia or a little longer; stigmas 2.
In sphagnum bogs and shallow water, Anticosti to Hudson Bay and the Northwest Territory, south to Maine, New York, northern Pennsylvania, Illinois and Iowa. Also in Europe and Asia. Summer.
Culms in small tufts from long creeping rootstocks, pale green, smooth, stiff, erect, 3'-8' high. Leaves involute, about \" wide, shorter than to exceeding the culm; spikes 5 or 6, androgynous, sessile and aggregated into an ovoid dense head 3 1/2-7 1/2 long, 5" wide or less, appearing like a solitary spike; perigynia ovate or ovate-oval, about 1 1/2" long and 1" wide, slightly margined above, faintly several-nerved, plano-convex, gradually narrowed into a short serrulate beak, the orifice oblique or in age slightly bidentate; scales ovate, brownish, membranous, obtuse to cuspidate, about equalling the perigynia; stigmas 2.
In dry soil, Manitoba to British Columbia, south to Iowa, Kansas and Colorado. Also in Europe and Asia. June-Aug.
Light green, culms slender, sharply 3-angled, smooth-ish, or rough at least above, 1°-2° tall, from long creeping rootstocks. Leaves 3/4"-2" wide, flat or nearly so, much shorter than the culm; bracts short, subulate from a broader base, or wanting; spikes several, androgynous or gynaecandrous, clustered in a terminal linear-oblong to ovoid-oblong head 6"-18" long, 3"-5" wide, the lower ones rarely compound; perigynia ovate, dark brown at maturity, 1 1/2"-2" long, faintly nerved, sharp-margined, tapering into a flat serrate beak shorter than the body; scales ovate or ovate-lanceolate, brownish, hyaline-margined, acute or cuspidate, usually exceeding the perigynia; stigmas 2.
In dry soil, Michigan to British Columbia, south to Nebraska, Kansas, New Mexico and Nevada. Rarely ad-ventive eastward. June-Sept.