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..
Glabrous, culms rather stout, erect, sharp-angled, smooth, or rough above, 1°-3° tall, phyllopodic, from stout, long-creeping rootstocks. Leaves pale green, 1 1/2"-4" wide, rough-margined, their sheaths more or less nodulose; lower bract foliaceous, shorter than to exceeding culm, the upper much shorter and narrower; staminate spikes commonly 2, stalked; pistillate spikes 2-5, dense, oblong-cylindric, erect, 9"-25" long, 3"-4 1/2 in diameter, sessile or the lower short-stalked; perigynia ascending, elliptic or somewhat obovate, prominently several-ribbed when mature, short-beaked, the beak 2-toothed; scales ovate or lanceolate, obtusish to strongly acuminate, dark with a green midvein, the upper shorter than the perigynia; stigmas 2.
South Dakota and Nebraska to Oregon, California and New Mexico. May-Aug.
C. subspathacea Wormsk. Fl. Dan. 9: 4. pi. 1530. 1816.
Glabrous, culm stiff, phyllopodic, smooth, 1'-7' tall, from slender elongated rootstocks. Leaves rigid, smooth, 3/4"-1 1/4" wide, the margins strongly involute; lower bracts foliaceous, somewhat spathe-like; staminate spike solitary, stalked; pistillate spikes 1-3, erect, sessile or very short-stalked, 3"-6" long, 1 1/2"-2" in diameter, closely 4-15-flowered; perigynia oval or ovoid, coriaceous, very short-beaked, pale green, faintly few-nerved, densely puncticulate, about 1 1/2" long; scales ovate or ovate-oblong, obtuse or acute, shorter than or equalling the perigynia; stigmas 2.
Greenland to Hudson Bay. Also in northern Europe and Asia. Intergrades with the next. July-Aug.
C. cuspidata Wahl. loc. cit. 164. 1803. Not Host, 1801.
Glabrous, culm slender but stiff, phyllopodic, smooth, erect, 4'-i8' tall, from slender elongated rootstocks. Leaves very narrowly linear, 1"-2 1/2" wide, rarely overtopping the culm, the margins revolute; lower bract similar, not spathe-like; staminate spikes 1 or 2, stalked; pistillate spikes 2-4, slender-stalked or the upper sessile, erect, 15-40-flowered, 5"-15" long, 2"-3 thick; perigynia ovate-elliptic, coriaceous, pale, faintly few-nerved, densely puncticulate, ascending, 1 1/2" long, tapering into a very short entire beak; scales ovate, reddish-brown or chestnut, with a green midvein, acute or cuspidate, somewhat longer than the perigynia; stigmas 2.
In salt marshes, Greenland to Hudson Bay. south to Quebec. Also in arctic Europe. Intergrades with the next. July-Aug.