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 or perennial sedges. Culms leafy below. Spikelets umbellate or capitate, terete, several to many-flowered, subtended by a 1-many-leaved involucre, their scales spirally imbricated all around, mostly deciduous, all fertile. Perianth none. Stamens 1-3. Style 2-3-cleft, pubescent or glabrous, its base much enlarged, falling away from the summit of the achene at maturity. Achene lenticular, biconvex, or 3-angled, reticulated, cancellate, or longitudinally ribbed or striate in our species. [Greek, in allusion to the fringed style of some species.]
Style 2-cleft; achene lenticular or biconvex.
Culms 8'-3° tall; spikelets umbellate; style mostly pubescent.
Perennial; leaves involute.
Scales chestnut-brown, shining, coriaceous.
Scales yellow-brown, membranous, dull.
Scales, at least the lower, pubescent or puberulent.
Annual; roots fibrous; leaves flat.
Culms 1-4' tall, very slender; spikelets capitate; style glabrous below.
Style 3-cleft; achene 3-angled.
Umbel mostly simple; spikelets ovoid to oval; achene reticulated.
Umbel mostly compound; spikelets linear; achene smooth or nearly so.
Perennial by a thickened base, glabrous, culms stiff, slender, 3-angled, wiry, 1°-3° tall, usually longer than the strongly involute rigid leaves. Leaves about 1" wide when unrolled, their sheaths often brown; leaves of the involucre 3-6, erect, the longer sometimes exceeding the usually compound umbel; umbel several-rayed, the rays nearly erect, 2'-6' long; central spikelets of the umbels and umbellets sessile, the others pedicelled; spikelets ovoid or ovoid-cylindric, acute, 2 1/2"-6" long, about 1" in diameter; scales oval, obovate, or orbicular, obtuse or orbicular, obtuse or subacute, coriaceous, glabrous, dark brown with a green midvein; stamens 2; style 2-cleft; achene lenticular, obovate, brown, reticulated.
In marshes and shallow water, New York to Florida, along the coast. Bermuda. Erroneously referred in first edition to the tropical American F. spadicea (L.) Vahl, which has longer spikelets. July-Sept.