570 CYtERACE^E. (SEDGE FAMILY.) 



2. CYPERUS proper. Achene triangular ; spikelets usually many-flowered, 

 more or less flattened ', with cannate scales, the rhachis marginless or nearly 

 so (winged in n. 12). 



* Stamen 1 ; spikelets short and small (1^-5" long) in globular heads, ovate or 



linear-oblong, many -flowered ; achene oblong -obovate to linear. 

 -^ Low annuals ; involucre 2- 3-leaved ; heads few; scales pointed. 



6. C. aristatUS, Rottb. Dwarf (1-5' high); spikelets chestnut-brown, 

 oblong becoming linear, 7 - 13-flowered, in 1-5 ovate heads (sessile and clus- 

 tered, or short-peduncled) ; scales nerved, tapering to a long recurved point ; 

 achene oblong-obovate, obtuse. (0. inflexus, Muhl.) Sandy wet shores; 

 common. Sweet-scented in drying. 



7. C. acuminatus, Torr. Slender (3 - 12' high) ; spikelets ovate, be- 

 coming oblong, 1 6 - 30-flowered, pale; scales obscurely 3-nerved, short-tipped ; 

 achene oblong, pointed at both ends. Low ground, 111. and southwestward. 



+-*-Tall perennial (1 -4 high) ; heads many, greenish ; scales pointless. 



8. C. calcaratus, Nees. Culm obtusely triangular ; leaves and involucre 

 very long, keeled; umbel compound, many-rayed; spikelets ovate (l^ x/ long), 

 in numerous small heads achenes pale, linear, on a slender stipe ; scales nar- 

 row, acutish, obscurely 3-nerved. (C. virens, Grau, in part; not Michx. C. 

 Luzulae, var. umbellatus, Britt.) Wet places, Del. to Fla. and Tex. 



* * Stamens 3 (2 in C. fuscus) ; spikelets clustered on the rays of a simple umbel 



(or in a single sessile head) ; scales mostly green or greenish and many-nerved, 

 abruptly sharp-pointed ; achene obovate, sharply triangular. 

 +-Low annuals. 



9. C. compressus, L. Culms 3-9' high, with a simple sessile or a few 

 umbellate clusters of oblong to linear spikelets (15 -30-flowered and 3-8" 

 long) with crowded strongly keeled and very acute pale scales. Sterile fields 

 along the coast, Md. to Fla. and Tex. ; also adventive near Philadelphia. 



C. Ftfscus, L. Of similar habit; spikelets much smaller (2-4" long), 

 the thin brown scales (greenish only on the keel) barely acutish and very 

 faintly nerved. Revere Beach, Mass. (Young); on ballast at Philadelphia. 

 (Adv. from Eu.) 



*- H- Perennial, propagating from hard clustered corms or bulb-like tubers. 



10. C. Schweinitzii, Torr. Culm rough on the angles (1 -2 high) ; um 

 bel 4 - 8-rayed, rays very unequal, erect ; spikelets loosely or somewhat remotely 

 6 - 12-floivered, with convex many-nerved scales ; joints narrowly winged. Dry 

 sandy shores and ridges, western N. Y. and Penn. to Minn, and Kan. 



11. C. filiciilmis, Vahl. Culm slender, wiry, often reclined (8-15' 

 high); leaves linear (^-2" wide) or filiform ; spikelets numerous and clustered 

 in one sessile dense head, or in\-l additional looser heads on spreading rays of 

 an irregular umbel; joints of the axis naked; scales blunt, greenish. Dry 

 sterile soil ; common, especially southward. 



12. C. Grayii, Torr. Culm thread-form, wiry (6-1 2" high); leaves al- 

 most bristle-shaped, channelled ; umbel simple, 4-6-rayed; spikes 5-10 in a 

 loose head, spreading ; joints of the axis winged ; scales rather obtuse, greenish- 

 chestnut-color. Barren sands, Plymouth, Mass., to N. J., near the coast. 



