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..
Annual, culms tufted, slightly compressed, very slender, rather stiff, striate, bright green, 8-2° tall. Upper sheath obliquely truncate or i-toothed; spike-let ovoid, obtuse or subacute, many-flowered, 3"-6" long, nearly 2" in diameter; scales broadly ovate, obtuse, pale greenish-brown with a darker midvein, broadly scarious-margined, firm, tardily deciduous; bristles 6, rigid, downwardly or rarely upwardly barbed, about as long as the achene and tubercle; stamens 3; style 3-cleft; achene obovoid, pale, trigonous, strongly reticulated, longitudinally about 18-ribbed; tubercle cap-like or conic, nearly or quite as large as the achene.
In wet soil, Massachusetts -to Pennsylvania, Florida and Texas, near the coast. July-Sept.
Eleocharis Torreyana Boeckl. Linnaea 36: 440. 1870.
Annual, culms finely filiform, densely tufted, somewhat 4-sided, erect or reclining, often proliferous by developing secondary culms in the axils of the spike-let, sometimes rooting at the summit, 2'-8' long. Upper sheath obliquely truncate; spikelet oblong, subacute, terete or nearly so, much thicker than the culm, many-flowered, 1 1/2"-2. 1/2" long; scales ovate, acute, brownish-red with a green midvein and lighter margins, early deciduous except the lowest which is commonly larger than the others, persistent and bract-like; bristles 3-6, slender, shorter than or equalling the achene; stamens 3; style 3-cleft; achene white, 3-angled, obovoid, smooth, minute; tubercle conic-pyramidal, much shorter than the achene.
Eleocharis melanocarpa Torr. Ann. Lye. N. Y. 3: 311. 1836.
Perennial by short rootstocks, culms flattened, striate, tufted, slender, erect, wiry, 10'-20' tall, sometimes proliferous. Upper sheath truncate, 1-toothed; spikelet oblong or cylindric-oblong, obtuse, 3"-6" long, 1 1/2-2" in diameter, many-flowered, thicker than the culm; scales ovate, obtuse, brown, with a lighter midvein and scarious margins; bristles 3-4, fragile, downwardly hispid, equalling or longer than the achene, fugacious or perhaps sometimes wanting; stamens 3; style 3-cleft; achene 3-angled, ob-pyramidal, black, smooth, its superficial cells nearly quadrate; tubercle depressed, covering the summit of the achene, light brown, pointed in the middle.
In wet sandy soil, eastern Massachusetts and Rhode Island to Florida, near the coast. Also in northern Indiana. July-Sept.