538 CYPERACE^E. (SEDGE FAMILY.) 



31 . C. COmpressus, L. Umbel simple or compound, often sessile, shorter 

 than the 4 - 6-leaved involucre; spikelets spreading, linear, flat, 12-30-flow- 

 ered ; scales ovate, acuminate, closely imbricated, keeled ; nut broadly obovate, 

 acute-angled, black and shining ; culms obtuse-angled, longer than the pale 

 green leaves. Cultivated grounds. July - Sept. (T) Culms 4' - 12' high. 

 Umbel spreading, sometimes reduced to few spikelets or a single one. Spike- 

 lets somewhat glaucous, 4" - 6" long, serrated by the projecting points of the 

 scales. 



32. C. viSGOSUS, Ait. Umbel simple, of 3 - 5 short erect rays ; involucre 

 elongated, 3-leaved ; spikelets several in a cluster, lanceolate, compressed, 

 1 2 - 20-flowered ; scales whitish, ovate, acuminate, loosely imbricated in fruit, 

 hispid-serrulate on the keel, the broad margins embracing the pear-shaped 

 acutely angled nut ; culm flattened on one side, rounded on the other, as long 

 as the slender keeled leaves. Dry sandy soil, South Florida. May -Nov. 



- Culms 9'- 15' high, straw-color, like the leaves. Spikelets \' long. 



* * Spikelets numerous in compact globular oblong or cylindrical heads. 



33. C. fuligineus, Chapm. Head solitary, globose, shorter than the 

 2-leaved involucre ; spikes lanceolate, acute, compressed, 8 - 12-flowered ; scales 

 (black) ovate, obtuse or emarginate, mucrouate ; nut oblong-obovate ; culms 

 filiform, obtuse-angled, thrice the length of the narrow rigid leaves. Key 

 West. Nov. Culms ^-l high. Sheaths of the leaves blackish. Head 

 5" in diameter. Scales 9-nerved. 



34. C. filiculmis, Vahl. Umbel of 1 - 2 spreading rays or none ; involu- 

 cre 3 - 4-leaved ; spikelets 15-20, in a dense globose head, linear-lanceolate, 

 6- 10-flowered ; joints of the rachis barely margined ; scales (greenish) ovate, 

 obtuse or emarginate, short-mucronate, loosely imbricated ; nut obovate ; 

 culms (10' -15' high), slender, wiry, longer than the linear leaves. Dry 

 sandy soil. July - Sept. Heads \ e in diameter. 



35. C. Martindalei, Britton. Allied to the preceding, but taller (l- 

 2 high) ; umbel 2 - 8-rayed, spikelets compressed, acute ; scales closely imbri- 

 cated ; rachis winged. Dry pine barrens near the coast, West Florida. 



36. C. Grayii, Torr. Umbel of 4-6 erect rays, shorter than the 3-4- 

 leaved involucre ; spikelets 6 - 9 in a rather loose head, linear or linear-lanceo- 

 late, 5 - 7-flowered ; joints of the rachis winged ; scales (brownish) closely 

 imbricated (spreading in fruit), ovate or oblong, obtuse ; nut obovate ; culms 

 (8'- 12' high) filiform, wiry, longer than the bristle-shaped leaves. Dry 

 sandy pine barrens, North Carolina (Curtis), and northward. August - 

 Sept. 



37. C. OVUlaris, Torr. Umbel 3 - 6-rayed, rarely wanting ; heads small, 

 globose or oblong; spikelets (H"- 2" long) angular, obtuse, 2-4-flowered ; 

 scales ovate-oblong, obtuse, mucronate, closely imbricated ; nut oblong ; culms 

 smooth, rather acute-angled, mostly longer than the leaves. Wet or dry 

 soil, common and variable. August - Sept. Culms - 2 high. Heads 2"- 

 3" in diameter. 



38. C. retrofractUS, Torr. Umbel of about 8 slender (2' -6' long) 

 rays, longer than the involucre: heads obovate ; spikelets subulate, reflexed- 



