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..
Mostly annual sedges, with slender erect culms, leafy below, the leaves narrowly linear or filiform, with ciliate or pubescent sheaths. Spikelets umbellate, capitate or solitary, subtended by a 1-several-leaved involucre, their scales spirally imbricated all around, mostly deciduous. Flowers perfect. Perianth none. Stamens 2 or 3. Style 2-3-cleft, glabrous, its base much swollen and persistent as a tubercle on the achene as in Eleocharis. Achene 3-angled, turgid or lenticular. [Greek, referring to the narrow leaves.]
Annual, roots fibrous, culms filiform, densely tufted, erect, grooved, smooth, 2'-10' tall. Leaves filiform, roughish, much shorter than the culm, their sheaths more or less pubescent with long hairs; involucral leaves 1-3, setaceous, shorter than, or one of them exceeding the inflorescence; spikelets narrowly oblong, somewhat 4-sided, 2 1/2"-4" long, less than 1" thick, several in a terminal simple or compound, sometimes capitate, umbel, or in depauperate forms solitary; scales oblong, obtuse or emar-ginate, puberulent, dark brown with a green keel; stamens 2; style 3-cleft; achene yellow-brown, narrowed at the base, very obtuse or truncate at the summit, i" long, 3-angled, transversely wrinkled; tubercle minute, depressed.
In dry or moist soil, Maine to southern Ontario, Minnesota, Florida, Texas, California and tropical America. July-Sept.