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..
Similar to C. Leersii, culms caespitose, very slender, wiry, rather stiff, erect, 1°-2° tall, slightly roughened above. Leaves 1/2"-1" wide, flat, shorter than the culm; bracts very short or lowest occasionally developed; spikes 2-4, the lateral usually pistillate with 1-10 widely spreading perigynia, nearly globular, somewhat separated, 2" in diameter, the terminal one longer and gynaecandrous or staminate; perigynia brownish at maturity, plano-convex, ovate, broadest near base, \\" long, about \" wide, faintly few-nerved on the outer face, nearly nerveless on the inner, thickened, spongy and rounded at base, contracted into a rough 2-toothed beak one-fourth to one-third as long as the body, its teeth very short, erect, the suture on inner side inconspicuous; scales ovate, usually very obtuse, much shorter than the perigynia.
Wet soil, eastern Quebec to Hudson Bay, British Columbia, Florida and Arizona. May-July.
Carex sterilis Willd. (C. scirpoides Schk.) differing by rough-edged perigynia tapering into a very rough beak, and not much exceeding the obtusish scales, the plants often partly or wholly dioecious, occurs from New York and New Jersey to Ontario and Indiana.
C. interior capillacea Bailey, Bull. Torr. Club 20: 426. 1893.
C. scirpoides capillacea Fernald, Rhodora 10: 47. 1908.
C. delicatula Ricknell, Bull. Torr. Club 35: 495. 1908. Not C. B. Clarke, 1908.
C. Howei Mackenzie, Bull. Torr. Club 37: 245. 1910.
Culms caespitose, capillary and slender, spreading, 6-20 long, roughened above Leaves about i" wide, usually involute, exceeding culms; bracts short; spikes 2-4, the lateral usually pistillate with 1-10 widely spreading perigynia, nearly globular, separated, 2" in diameter, the terminal longer and gynaecandrous or staminate; perigynia green or brownish at maturity, plano-convex, ovate, broadest at base, 1 1/4" long, about 3" wide, strongly nerved on outer face, less on inner, spongy and rounded at base, tapering into a rough 2-toothed beak about one-third as long as the body, its teeth very short, erect, the suture on inner side inconspicuous; scales ovate, obtuse to acutish, shorter than perigynia.
Wet soil, Massachusetts and New Hampshire to New York, New Jersey and Pennsylvania. June-July.
C. cephalantha Bicknell, Bull. Torr. Club 35: 493. 1908.
Culms slender to stoutish, stiff or in shade weak, erect or rarely spreading, 4'-3° tall, rough, at least above. Leaves i"-2" wide, shorter than the culm; bracts very short or sometimes bristle-form; spikes 2-8, subglobose or short-oblong, closely contiguous to widely separated, about 2 1/2" thick, 3-40-flowered; staminate flowers basal; perigynia from lanceolate to broadly ovate, plano-convex, ascending when young, 1 1/4"-2" long, 1/2"-1" wide, spreading or reflexed when old, several-nerved on both faces, the nerves usually not conspicuous on inner face, thickened at base, tapering into a sharp-edged 2-toothed rough beak more than one-half as long as the body, the teeth and suture on inner side conspicuous; scales ovate, hyaline, acutish to acuminate, shorter than the perigynia; stigmas 2. In moist soil throughout the continent north of Mexico; often locally absent. Also in Europe and Asia. Presenting many forms. May-July.