205 



A Preliminary List of North American Species of Cyperus, with 



Descriptions of new Forms. 



By N. L. Britton. 



(A) Sub-genus Pycreus, Beauv. 



* Umbel sitnple or capitate, rarely slightly conipoiind. 



t Superficial cells of the achenium oblong. 



1. Cyperus Jlavescens,!^. Canada to Texas throughout east- 

 ern North America ; also in northern Mexico, Brazil, southern 

 Europe, northern Africa and western Asia. 



t t Superficial cells of the achenium quadrate. 



2. C. diandrus, Torrey. Throughout eastern North 

 America, extending westward to Arkansas and New Mexico. 

 (Fendler, No. 869.) 



Var. castaneiis, Torrey. {C. Elliottianiis, Roem. and Schultes, 

 Mant. ii., p. 100.) With the type. I cannot agree with Mr. C. 

 B. Clarke, (Journ. Linn. Soc, xxi., p. 65) in regarding this plant 

 as a distinct species under the name C. rivularis, Kunth. The 

 varieties eliLta and dcpanpcrata which he proposes (1. c.) are, in 

 my opinion, but forms of the variable C. diandrus. There is 

 still another form, characterized by elongated, spikelets, which 

 has been collected by Hunter in Lincoln Co., N. C, and by Leg- 

 gett at Summit, N. J. 



Var. CAPITATUS, n. var. Inflorescence a single capitate cluster 

 appearing somewhat lateral ; involucre of one or two elongated 

 leaves with one or two bracts; glumes generally brown-mar- 

 gined. Texas and northern Mexico j:o California. Here 1 in- 

 clude the var. castaneiis of Watson in Botany of California, ii., p. 

 214 ; No. 1949 of C. Wright's New Mexican Collection, and No. 

 49a of Dr. Palmer's Chihuahuan Collection' of 1885. 



3. C. bipartitus, Torrey. New Orleans, La., (Dr. Ingalls 

 in Torrey Herbarium.) This appears to be distinct, but more 

 specimens are needed to establish its relationship ; it may be but 

 a single-spiked form or variety ot" C. diandrus. 



4. C. Nuttallii, Eddy in Sprang. Neue Entdeck., i., p. 

 240; Torrey. In salt meadows along the Atlantic and Gulf 

 coasts (Curtiss, N. A. Plants, 3050.) For synonomysee Torrey, 

 Ann. Lye, iii., p. 252, C. Cleaveri, Torrey, is but a depauper- 

 ate, single spiked form, of this species. 



