324 North American Cyperacea. 



forming somewhat compound corymbs. Scales membranaceous, some- 

 what pubescent, chestnut coloured ; the summjt a little cleft each side of the 

 midrib, which is produced into an awn-like cusp or bristle about 2 lines 

 long and recurved so as to give the spikes a squarrose appearance. 

 Bristles 3 — 4, very slender, about two-thirds the length of the nut, re- 

 trorsely scabrous. Nut large, nearly orbicular, much compressed, dark 

 brown, and polished, tipped with the minute base of the style. 



Hab. Salt marshes, and ditches near salt water ; not found 

 far from the sea shore ; Maine to Florida. 



Obs. Mr. Arnott thinks that the Scirpus affinis of Roth and 

 N. ab Esenb. (1. c.) approaches so near S. maritimus, that the 

 two species cannot always be distinguished, and in this opinion 

 I agree. 



13? jluviatilis. Culm triquetrous, leafy ; umbel somewhat 

 compound, shorter than the involucre ; spikes ovate, (large and 

 thick,) acute ; scales ovate, lacerately 3-toothed ; the midrib 

 produced into a brisde; nut obovate, triangular, narrowed 

 downward, (dull,) acuminate, as long as the (6) rigid bristles. 



S. marhimus, Elliott, s7c. 1. p. 86 ? •, Gray! Gram. Sf Cyp. part 1, 

 no. 82, (in part). 



S. macrostachyos, Muhl. ! gram. p. 45, (in part.) 



Culm 2 — 4 feet high, acutely triangular, smooth, leafy below. Leaves 

 as tall as the culm, more than half an inch broad, smooth on the margin 

 and keel. Umbel composed of 10 — 20 spikes; the principal rays about 

 5, 1 — 3 inches long, semiterete ; the subdivisions bearing at their extre- 

 mity 2 — 3 or more spikes in a dense cluster. Involucre 3 — 5-leaved, 

 much longer than the umbel. Spikes nearly an inch long and about 

 half an inch in diameter, rather acute even in fruit. Scales thin and 

 scarious, pubescent, rarely emarginate, of a pale brown colour, lacerately 

 ]-toothed each side of the midrib, which is produced into a flat recurved 

 cusp or short bristle. Bristles mostly 6, straight and stiff, unequal ; the 

 longest somewhat exceeding the point of the nut. Style unequally 3- 

 cleft, rarely 4-cleft. Nut more than 2 lines long, triangular wnth the 

 sides equal and nearly plane, gradually narrowed downward, abruptly 

 acuminated, of a dull grayish colour, very minutely papillose. 



Hab. Swamps along the borders of rivers and lakes, 

 always in fresh or only slightly brackish water. Common in 



.V 



