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..
Carex tenella Schk. Riedgr. 23. f. 104. 1801. Not Thuill.
1799. Carex disperma Dewey, Am. Journ. Sci. 8: 266. 1824.
Light green, rootstocks elongated, very slender, culms almost filiform, rough, commonly reclining, 6'-2° long. Leaves soft, 1/2"-3/4" wide, spreading, usually shorter than the culm; spikes very small, androgynous, only 1-5-flowered, distant or the upper close together, the bracts absent or bristle-form; perigynia ovoid-ellipsoid, very thick, hard, finely many-nerved, about 1" long and 3/4' thick, tipped with a very minute, smooth, entire beak; scales ovate, hyaline, acute to cuspidate, shorter than or the lower equalling the perigynia; achene closely filling perigynium; stigmas 2.
In bogs, Newfoundland to British Columbia, New Jersey, Pennsylvania, Indiana, Michigan, Colorado and California. Also in Europe and Asia. June-Aug.
Carex trisperma Dewey, Am. Journ. Sci. 9: 63. 1825. Carex trisperma var. Billingsii Knight, Rhodora 8: 185. 1906.
Bright green, culms filiform, weak, often divaricate-spreading above lowest bract, usually reclining or spreading, very slightly roughened, 1°-2 1/2° long, the rootstocks slender, often elongated. Leaves flaccid, flat, 1" wide or less; spikes 1 to 3, only 1-5-flowered, gynaecandrous, widely separated, the lowest much exceeded by a bristle-form bract 1/2'-5' long; perigynia oblong, ascending, green, 1 1/4"-2" long, nearly 1" wide, very finely many-nerved, narrowed at both ends and tipped with a very short, nearly entire beak, the margins smooth or nearly so; scales ovate or ovate-lanceolate, hyaline with a green mid-vein, acute, somewhat shorter than the perigynia; stigmas 2.
Light green, culms very slender or filiform, erect or reclining, rough above, 8-2° long, loosely caespitose and stoloniferous. Leaves 1/4"-1" wide, flat, usually much shorter than the culm; spikes 2-4, gynaecandrous, subglobose, few-flowered, about 2!" in diameter, usually bractless, densely aggregated into an ovoid or suborbicular head; perigynia pale, oblong-obovoid, densely puncticulate, coriaceous, obscurely nerved, narrowed at both ends, 1 1/4"-1 3/4" long, a little more than 3/4" wide, almost beakless, spreading, smooth or nearly so; scales white with green midrib, acute or obtusish, about equalling the perigynia; achene nearly filling perigynium; stigmas 2.
In bogs. New Brunswick and Hudson Bay to Manitoba, south to Maine, Massachusetts, central New York and Minnesota. Local. Also in Europe and Asia. Summer.