NoTth American Cijperacca. 275 
28. Cyperus virens, Michx. 
Culm acutely triangular; umbel compound ; involucre many- 
Jeaved, very long; involucels nearly equalling the partial rays; 
spikelets ovate and ovate-lanceolate, much compressed, col- 
lected in dense globose heads, 12 — 20-flowered ; rachis naked ; 
scales oblong-lanceolate, acute ; stamen 1 ; nut oblong, trique- 
trous, acute at each end. 
C. virens, Miclix.! fl. 1. p. 28 ,- Pursh,fl. 1. p. 52; Muhl.! grain, j). 
24; Elliott, sk. 1. p. 66; Vahl, enum. 2. p. 353; Rotm. Sf Schult, syst. 
2. p. 210 ; Spreng. syst. 1. 226. 
C. glomeratus, Walt. fl. Car. p. 70? 
Culm 2 — 5 feet high, thick and firm, very acutely triquetrous, tlie 
angles sharply serrulate near the summit. Leaves nearly as long as 
the culm, 4 — 5 lines wide, rough on the edges and keel, the sides 
folded together. Umbel with 5 — 7 very unequal raj^s ; partial rays 
nearly an inch long, each bearing a dense head of about 20 spikelets^ 
Ochrece bifid. Involucre 6 — 8 times as long as the umbel ; involucels 
foliaceous, about as long as the partial umbels. Spikelets varying from 
ovate to lanceolate, rather obtuse, 3 — 5 lines long, and a line and a half 
broad. Scales carinate, greenish. Interior scales entirely wanting. 
Stamen always solitary. Style 3-cleft. Nut acute at each end, dull 
yellow. 
Hab. In swamps: confined to the Southern States. Wil- 
mington, North Carolina, Mr. Curtis ! ; South Carolina, £/Zzo^^.'; 
Georgia, Muhlenberg.' ; Middle Florida,!??-. Chajjman ! ; New 
Orleans, Dr. Ingalls! 
29. Cyperus vegetus, TVilld. ? 
Culm obtusely triangular, smooth on the angles; umbel com- 
pound ; involucre 4-leaved ; involucels bracteiform, shorter 
than the partial rays ; spikelets ovate, much compressed, col- 
lected in dense globose heads, 9 — 16-flo\vered ; rachis naked ; 
scales oblong, acute, somewhat incurved ; stamen 1 ; nut lan- 
ceolate, attenuated to a long point, tumid at the base. 
