536 CYPERACE.E. (SEDGE FAMILY.) 



3. Umbel compound or decompound, diffuse : spikelets ^-ranked, compressed, 

 many-flowered, 3-10 in a cluster at the summit of the general and partial 

 rays : scales closely imbricated, 3 - T -nerved, decurrent on the rachis : sta- 

 mens 3. 



* Culms terete, knotted, leafless: involucre very short: nut oblong. 



21. C. articulatus, L. Umbel compound, many-rayed, spreading or re- 

 curved ; involucre of three bract-like pungent leaves ; spikelets long (-'- 1.}' 

 long), linear, spreading, 30 - 40-flowered ; scales whitish, oblung, obtuse, 7- 

 nerved on the back, thrice the length of the linear-oblong dull nut ; rhizoma 

 creeping, bearing tuber-like buds; culms stout (3 -5 high), tumid at the 

 sheathed base. Marshes near the coast, Florida to South Carolina. Au- 

 gust - Sept. 2/ Flowers mostly abortive. 



* * Culms 3-angled, knotless : involucre leafy : nut obovate. 



22. C. Haspan, L. Umbel many-rayed, decompound, spreading, the 

 filiform rays mostly longer than the 2-leaved involucre; spikelets small (4"- 

 5" loug),3-5 in a cluster, linear, acute, 20 - 40-ttowered ; scales light reddish 

 brown, very small, oblong, mucronate, 3-uerved, free at the apex ; nut white, 

 granular-roughened ; culms tender, sharply angled ; leaves linear, smooth, 

 shorter than the culms (1- H), often reduced to membranaceous sheaths. 

 Ponds and ditches. July - Sept. 



23. C. dentatus, Torr. Umbel compound, erect, 4-7-rayed, shorter 

 than the 3-4-leaved involucre; spikelets 3-5 in a cluster (3" -1" long), 

 ovate-oblong, obtuse, flat, 12-30-flowered ; scales ovate, acute, compressed, 

 7-nerved on the green keel, membranaceous on the reddish brown sides, spread- 

 ing at the apex; nut minute, whitish ; rhizoma creeping, bearing tubers; 

 culms slender (1 high), obtuse-angled, longer than the rigid keeled leaves. 

 Sandy swamps and banks, South Carolina ( Torrey), and northward. Sept. 

 11 Rays 1'- 2' long. 



24. C. Lecontei, Torr. Umbel compound, erect, 6-12-rayed, shorter 

 than the 3-leaved involucre ; spikelets commonly three in a cluster, oblong or 

 linear-oblong, obtuse, flat, 30 - 70-flowered ('-!' long) ; scales closely imbri- 

 cated, ovate, obtuse, compressed, yellowish, faintly 7-nerved, appressed at the 

 apex; nut minute, blackish ; culms rigid, obtuse-angled, as long as the rigid 

 leaves. Low sandy places along the coast, East and West Florida. July - 

 Sept. ")l Rhizoma creeping. Culms 6'- 12' high. Rays 2' -6'. long. 

 Hachis with very short joints. Whole plant pale straw-color. 



4. Umbel simple or compound : spikelets many-flowered, compressed, numerous in 

 a cluster, forming more or less dense heads at the summit of the common and 

 partial rays : rachis wingless : stamen solitary. 



* Umbel compound: spikelets orate or oblong, flat: scales 3-nerved , concave on 

 the back, acute: nut minute, lanceolate or oblonrj. 



25. C. virens, Michx. Umbel spreading, compound, many-rayed ; invo- 

 lucre 4-6-leaved, many times longer than the umbel ; spikelets (4" -6" long, 

 and about 20 in a cluster) oblong, 30 -40-flowered, pale green ; scales oblong, 

 lanceolate, straight; nut lanceolate, acute at each end; culms stout (2 -4 



