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..
Cyperus Bushii Britton, Man. 1044. 1901.
Perennial by tuber-like corms. Leaves 1 1/2"-2" wide, smooth; culms smooth, 1°-2° high, longer than the leaves; longer involucral bracts much exceeding the umbel; umbel capitate, or with 1-5 rays; spikelets loosely capitate, flat, linear, acute, 4"-8" long; scales firm, shining, oblong, mucronate, strongly about 11-nerved falling away from the persistent axis of the spikelet at maturity; achenes oblong, 3-angled, nearly twice as long as thick, apicu-late, two-thirds as long as the scale, sometimes persistent after the scales fall.
Perennial by thickened tuber-like joints of the root-stocks, culm rather stout, 1°-4° high, often equalled by the leaves. Leaves 1 1/2"-2" wide, smooth, nodulose, the midvein prominent; leaves of the involucre 4-6, spreading, the longer much exceeding the inflorescence; umbel several-rayed, compound, the primary rays often 4' long; spikelets ovate, flat, many-flowered, light green, densely capitate, 2"-3" long; scales keeled, condupli-cate, i-nerved, curved, acute, longer than the linear 3-angled slightly stalked achene; stamen 1; style 3-cleft.
In marshes, New Jersey to Florida, Kentucky, Missouri, Kansas and Texas. Also in the Bahamas. July-Sept.
Annual, culms very slender, tufted, 3'-15' tall, longer than or equalling the leaves. Leaves light green, usually less than 1" wide, those of the involucre much elongated; umbel 1-4-rayed, simple; rays short; spikelets flat, ovate-oblong, obtuse, 2"-4" long, many-flowered, densely capitate; scales oblong, pale green, 3-nerved, coarsely cellular, conduplicate, with a short sharp more or less recurved tip; stamen 1; style 3-cleft; achene sharply 3-angled, gray, oblong, narrowed at each end, about one-half as long as the scale.
In moist soil, Illinois to South Dakota, Louisiana, Iowa, Kansas, Texas, Oregon and California. July-Oct.
Cyperus fuscus L. Sp. PI. 46. 1753.
Annual, culms slender, tufted, 6-15' high, longer than or equalled by the leaves. Leaves rather dark green, about 1" wide, those of the involucre 4-6, the longer much exceeding the inflorescence; umbel several-rayed, somewhat compound, the rays short; spikelets linear, 2"-7" long, less than 1" wide, many-flowered, acute; scales ovate, subacute, becoming dark brown or remaining greenish on the keel, faintly about 3-nerved on the back, separating from the narrowly winged rachis as they mature; stamens 2 or 3; style 3-cleft; achene sharply 3-angled, oblong, pointed at each end, nearly as long as the scale.
Waste grounds and in ballast, eastern Massachusetts to New Jersey and Maryland. Adventive from Europe. July-Sept.