North Amtriraa Cijjjrrfirect. 357 
Tribe IV. RIIY.NCHOSPOKK.K. 
F'j>owEKS perfect or pol\"t(anioii.-j. Fpikks mostly lew- 
flowered. kScALES irreiruUirh luiiiricated, ul).~curcly disiichoiis 
or lrll'ariou.s. PiiiilGV.viUM u-sually .setilorm, or cup-slmped, 
rarely wanting. Nut conspicuously beaked with the |)er.-istent 
base of the style, or crowned with an articulated tubercle, 
mostly corrui^Mted or sculptiu'ed. 
A. Sh/U :>—:5-c/ef}. 
15. DTCHROMEXA, Iluharfl. 
Spikes compressed. Scales irregidaiiy imbricated on all 
sides, or fasciculate, many of them abortive. Sta.mkxs 3. 
Style 2-cleft. Nut somewhat lenticular, crowned witli the 
broad tuberculate persistent base of the style. Bristles 0. 
— Spikes sessile, aggregated in a terminal head ; involucre 
coloured (mostly white) at the base ; culm leafy. 
Dichromena, Btchard in Michx. f. 1. p. 37; Lrsflb. exa. 
fain. Cijp. p. 40, no. 47 ; Vahl, cnum. 2. p. 240; A', ah Esenh. 
in Limicea, 9. p. 291. 
Dichroma, Pers. syn. 1. p. -57 ; Muhl. gram. p. 13 ; Nutt. 
gen. 1. p. 31. 
Species of Schcenus, Linn., Kunth. 
1. DiCHROMEXA LEUCOCEPHALA, Mich.C. 
Culm triangular ; leaves somewhat concave, narrow; invo- 
lucre about 5-leaved, yellowish-white at the base ; nut truncate 
at the summit, transeversely rugose ; tubercle compressed, 
conical, acute, distinct, straight at the base. 
