CYPERACEAE. 



VOL. I. 



A large genus, the species about 125, widely distributed. Besides the following, some 5 others 

 occur in southern and western North America. Type species: Fimbristylis acuminata Vahl. 



Style 2-cleft ; achene lenticular or biconvex. 



Culms 8'-3 tall; spikelets umbellate; style mostly pubescent. 

 Perennial ; leaves involute. 

 Scales glabrous. 



Scales chestnut-brown, shining, coriaceous. 

 Scales yellow-brown, membranous, dull. 

 Scales, at least the lower, pubescent or puberulent. 

 Annual ; roots fibrous ; leaves flat. 



Culms i '-4' tall, very slender; spikelets capitate; style glabrous below. 

 Style 3-cleft ; achene 3-angled. 



Umbel mostly simple ; spikelets ovoid to oval ; achene reticulated. 

 Umbel mostly compound ; spikelets linear ; achene smooth or nearly so. 



1. F. castanea. 



2. F. interior. 



3. F. pubcrula. 



4. F. Bald'cviniana. 



5. F. I'ahlii. 



6. F. geminata. 



7. F. aiituuiiialis. 



i. Fimbristylis castanea (Michx.) Vahl. Marsh Fimbristylis. Fig. 784, 



Scirpns castaneits Michx. Fl. Bor. Am. i : 31. 1803. 

 Fimbristylis castanea Vahl, Enura. z : 292. 1806. 

 F. spadicea castanea A. Gray, Man. Ed. 5, 566. 1867. 



Perennial by a thickened base, glabrous, culms 

 stiff, slender, 3-angled, wiry, i-3 tall, usually 

 longer than the strongly involute rigid leaves. 

 Leaves about i" wide when unrolled, their sheaths 

 often brown ; leaves of the involucre 3-6, erect, 

 the longer sometimes exceeding the usually com- 

 pound umbel ; umbel several-rayed, the rays 

 nearly erect, 2' -6' long; central spikelets of the 

 umbels and umbellets sessile, the others pedicelled; 

 spikelets ovoid or ovoid-cylindric, acute, 22 "-6" 

 long, about i" in diameter; scales oval, obovate, 

 or orbicular, obtuse or orbicular, obtuse or sub- 

 acute, coriaceous, glabrous, dark brown with a 

 green midvein; stamens 2; style 2-cleft; achene 

 lenticular, obovate, brown, reticulated. 



In marshes and shallow water. New York to Flor- 

 ida, along the coast. Bermuda. Erroneously referred 

 in first edition to the tropical American F. spadicea 

 (L.) Vahl, which has longer spikelets. July-Sept. 



2. Fimbristylis interior Britton, n. sp. 

 Plains Fimbristylis. Fig. 785. 



Perennial, with short stolons, the base of 

 the culm slightly thickened. Culms loosely 

 tufted to solitary, very slender, smooth, 

 striate, somewhat compressed, i-2 high; 

 leaves rough-margined, involute, at least 

 toward the tip, i" wide or less, shorter 

 than the culms ; bracts of the involucre mostly 

 shorter than the umbel, ciliate; umbel a little 

 compound, its rays filiform; spikelets few to 

 several, ovoid to ovoid-oblong, acutish, 5" 

 long or less, many-flowered ; scales yellow- 

 brown, ovate, striate, mucronate or the 

 lower ones awned, glabrous, dull; stamens 3; 

 achene broadly obovate, blunt, cancellate in 

 many rows, chestnut-brown, nearly i" long. 



Colorado and Nebraska to Texas. Type col- 

 lected by Geo. E. Osterhout at Sterling, Logan 

 County, Colorado, Aug. 13, 1896. 



