636 cvPKRACE.'E. (ski)(;k family.) 



3. UihIh'I compound or ilecomjiouuil, diffnue : sjiikclets 2-runked, compressed , 

 muny-jlowered, 3-10 in a cluster at the summit of the (jenerul tiud partial 

 rai/s : scales closely imbricated, 'S-1 -nerved, decurrent on the rachis : sta- 

 mens 3. 



* Calms terete, knotted, ledjltss : inrulitrre very short : nut obluiiy. 



'2\. C. articulatus, L. Umliel cnmjxuuKl, iiiaiiy-niycfl, spreadiu^ or re- 

 furvid; iiivulucre of tliree bract-like |imi{^oiit leaves ; S]jikelet.s long (^' - 1.}' 

 long), linear, jspreadiug, 30- 4U Howered ; scales whitisli, oliiong, obtuse, 7- 

 nervecl on the back, thrice tlie leiigtli of the linear-oblong dull nut ; rliizonia 

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

 slieatiied base. — Marshes near the c<«ist, Florida to South Carolina. Au- 

 gust-Sept. ^ — Flowers mostly abortive. 



* * Culms 3-angled, knotUss : involucre leafy : nut ohovnte. 



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-tlowered ; scales ligiit reddish 

 brown, very small, oblong, mucronate, 3-nerved, free at tlie apex ; nut wliite, 

 granular-rongliened ; culms teuder, sharply angled ; leaves linear, smooth, 

 shorter tliau the culms (l°- 1^°), often reduced to membranaceous sheaths. — 

 Fonds and ditclies. July - Sept. 



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

 than the 3-4-leaved involucre; spikelets 3-5 iu a cluster {3"-7" hmg), 

 ovate-oblong, obtuse, flat, 12-30-tlowered ; scales ovate, acute, compre.ssed, 

 7-nerved ou tlie green keel, membranaceous on the reddish l)rown sides, spread- 

 ing at the apex; nut nn'nute, vvhitisii ; rliizoma creo])ing, bearing tul)ers; 

 culms slender (1° high), obtu.se-angled, longer than the rigid keeled leaves. — 

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

 2Z — Kays 1'- 2' long. 



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

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

 linear-oldong, obtu.se, fiat, 30 - 70-flowere(l (V-V long) ; scales closely imliri- 

 cated, ovate, obtuse, compressed, yellowish, faintly 7-nerved, appre.ssed at the 

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

 leaves. — Low sandy ]ilaces along the coast. East and West Florida. July - 

 Sept. % — Khizoma creeping. Culms 6'- 12' high. Rays 2'-6' long. 

 Itacliis with very short joints. Whole ])laiit pale straw-color. 



4. L mhel simple or compound: spikelets mnnyflowr-red, compressed, numerous in 

 a cluster, forming more or less dt-nse heads at the summit of the common and 

 partial rays : rachis wingless : stamen solitary. 



* Umbel compound : spikelets ovate or oblong, fat : scales 3-nerved , concave on 

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



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

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

 and aT)out 20 in a cluster) oblong, 30-40-flowere(l, pale green ; scales oblong 

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



