North American Ci/jjcracea. 357 



Tribe IX. RHYNCHOSPOREiE. 



Flowers perlect or polygamous. Spikes mostly few- 

 flowered. Scales irregularly imbricated, obscurely distichous 

 or trifarious. Perigynium usually setiform, or cup-shaped, 

 rarely wauting. Nut conspicuously beaked with the persistent 

 base of the style, or crowned with an articulated tubercle, 

 mostly corrugated or sculptured. 



A. Style 2 — 3-deff. 



15. DICHROMENx\, Richard. 



Spikes compressed. Scales irregularly imbricated on all 

 sides, or fasciculate, many of them abortive. Stamens 3. 

 Style 2-cleft. Nut somewhat lenticular, crowned with 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, Richard in Michx. ji. 1. p. 37; Lestib. ess. 

 fam. Cyp. p. 40, no. 47 ; Vahl, enum. 2. p. 240 ; N. ab Esenb. 

 in Lijincea, 9. p. 291. 



Dichroma, Pcrs. syn. 1. p. 57 ; Muhl. gram. p. 13 ; Ntctt. 

 gen. 1. p. 31. 



Species of Schoenus, Linn.y Kunth. 



1. Dichromena leucocephala, Michx. 



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, straijiht at the base. 



