26 CYPERACEAE. 



Stamen 1 : plants perennial. 4. C. surinanicnsis. 



Wings of the ractiis manifest. 



Leaves reduced to pointed slieaths. 



Involucral bracts numerous : spikelets broad, 



1.5-2 mm. wide, reddish-brown. ">. C. aJternifoUiis. 



Involucral bracts mostly 2 : spikelets slender 



about 1 mm. wide, pale. 0. C. Haspan. 



Leaves with elongate-linear blades. 7. C. rotuiidtts. 



Rachis of the spikelets deciduous. 



Rachis breaking up into 1-fruited joints : spikelets 



nearly terete. 8. C. speciosus. 



Rachis deciduous above the lower pair of scales. 



Achenes narrowly linear-oblong, 2V2— t times as 

 long as thick. 

 Spikelets distinctly flattened, several-many- 

 flowered. !!. c. Martindalei. 

 Spikelets nearly terete to a little flattened, 

 l-few-flowered. 

 Spikes obovoid, the lower spikelets reflexed. 

 Spikelets with appressed scales : achenes 



about 2 mm. long. Ic C. retrorsus. 



Spikelets with lax scales : achenes about 



1.5 mm. long. 11. C. Pollardi. 



Spikes cylindric. 12. C. Torrcyi. 



Achenes oblong to obovoid, not more than twice as 

 long as thick. 

 Spikelets with 1-4 achenes. 



Rachis wingless or narrowly winged. 



L'mbel simple: leaf-blades narrow. 13. C.tetragonus. 



Umbel compound: leaf-blades broad. 14. C.Hgularis. 



Rachis with broad membranous wings. 15. C. cchinatus. 



Spikelets with 5-10 achenes. 16. C. hrunneus. 



1. C. densus Link. Annual, 1-7 dm. tall: leaves generally 2 or 4; blades 1-3 

 mm. wide, smooth: umbel capitate, or 2-4 rays becoming 1-3 cm. long: 

 spikelets few, linear to linear-lanceolate, 5-8 mm. long, acutish: scales straw- 

 colored or yellowisli-green, ovate, 2 mm. long: achenes oval or oval-obovoid, 1 

 mm. long, brown, dull, barely i as long as the scale. [C. helvus Liebm.] — 

 Hammocks. — {Cuha, Ant.) 



2. C. paniculatus Eottb. Annual, 1-4 dm. tall : leaves often 3-6 ; blades 1-4 

 mm. wide, or sometimes narrower or even filiform, not firm: umbel with 3-8 

 rays 1-5 cm. long, or rarely nearly capitate: spikelets few, linear or linear- 

 lanceolate, 6-15 mm. long, acute: scales light chestnut-brown, oblong-lanceo- 

 late, 2-2.5 mm. long: achenes oblong, fully 1 mm. long, grayish, abruptly 

 apiculate, fully 4 as long as the scale. — Everglades. — F. K. {Ber., Bah., Cuba, 

 Ant.) 



3. C. compressus L. Annual, with scapes 7-25 cm. long: leaves light-green; 

 blades about 2 mm. wide : scapes smooth : umbel capitate or with 2-3 short 

 rays: spikelets narrowly lanceolate, acute, 8-20 mm. long, 3-4 mm. wide, very 

 flat, many-flowered: scales light-green with a yellow band on each side, ovate, 

 acuminate: achenes obovoid, obtuse, dull-brown, about J as long as the scale. — 

 Pinelands. — F. K. (Bah., Cuba, Ant.) 



4. C. surinamensis Eottb. Perennial, 2-12 dm. tall: leaves overtopped by the 

 scape; blades mostly 1.5-4 mm. wide, usually rough along the margins: scapes 

 rough above: umbels mostly compound, of generally 8-12 rays of various 

 lengths, several spikes sessile or clustered in the involucre: spikelets oblong or 

 linear-oblong, 5-12 mm. long, yellow, blunt, 40-50-flowered: scales ovate, 

 nearly 1.5 mm. long: achenes oblong, about 0.8 mm. long, brown, pinched at 

 both ends. — Everglades. — (Cuba, Ant.) 



5. C. altemifolius L. Perennial 0.5-2 m. tall: leaves without blades: scapes 

 often tufted: bracts of the involucre numerous, pliable, elongate-linear, spread- 

 ing or slightly drooping: umbel compound, the longer rays 2.5-9 cm. long or 

 more: spikelets ovate to linear-oblong, 1.5-2.5 mm. wide; scales spreading: 

 achenes obovoid, about 0.8 mm. long, brown. — Everglades. Xat. of Africa. 

 (Ber., Cuba, Ant.) — Umbrella-plant. 



