37(36). Culms (60-) 75-110 cm. tall; bracts 9 to 13; primary peduncles 9 to 



13; spikelets reddish-brown; achenes 0.4—0.5 mm. thick 



35. C. setigerus. 



37. Culms 15-50 (-65) cm. tall; bracts 5 to 10; primary peduncles 5 to 10; 



spikelets brown, buffy-brown or golden-brown; achenes 0.6-0.8 

 mm. thick 36. C. esculentus. 



38(35). Achenes mostly 0.3 to 0.5 times as long as the scales; spikelets 10-29 

 mm. long, 1-2 mm. broad, usually less than half as thick as broad 

 (39) 



38. Achenes mostly 0.6 to 0.8 times as long as the scales; spikelets 3.5-11 mm. 



long, 0.5-1 (-1.3) mm. broad, usually more than half as thick as 

 broad (40) 



39(38). Blades 2-8 mm. broad; most inflorescences with the longer peduncles 

 bearing a few short secondary ones; spikes 13-35 mm. long, 20-45 

 mm. thick, thus usually thicker than long, with 20 to 70 spikelets 



1-2 mm. broad, golden- or tawny-brown, with 5 to 20 scales 



37. C. strigosus. 



39. Blades 1.5-5 mm. broad; secondary peduncle formation rare; spikes 20-40 



mm. long, 15-27 mm. thick, thus usually longer than thick, with 

 14-45 spikelets 0.7-1.3 mm. broad, grayish-brown, with 3 to 6 

 scales 38. C tenuis. 



40(38). Perennial from black knotty subrhizomatous bases; inflorescence only 

 2-3 (-4) cm. long, of 3 to 6 essentially sessile spikes 10-25 mm. 

 long and 7-10 mm. thick, with 40 to 80 three-scaled spikelets; only 

 the lowest scale of each spikelet fertile and it enclosing the achene 

 (1.5-2.1 mm. long, 0.8-1 mm. thick) 39. C. huarmensis. 



40. Tufted perennials; inflorescence (1-) 2-15 cm. long, of 1 to 14 usually 



peduncled heads or spikes 7-30 mm. long and 7-20 mm. thick, 

 with 8 to 240 2- to 8-scaled spikelets in which only the terminal 

 scale is sterile, the rest all fertile; achenes 0.5-0.8 mm. thick (41) 



41 (40) . Spikes lax, 10-30 mm. long, with 8 to 30 spikelets (42) 



41. Heads or spikes dense (the spikelets touching), 7-15 mm. long, with 25 to 



240 spikelets (43) 



42(41). Scales 2.2-2.5 mm. long, 1.5-2 mm. wide; achene olive-brown, minutely 

 punctulate 40. C. Pringlei. 



42. Scales 2.5-3.5 mm. long, about 1 mm. wide; achene yellow-brown to browo., 



41. C hermaphroditiis. 



43(41). Achenes 1.8-2.2 mm. long; wings 1-2 mm. long; scales 1.2-2 mm. 

 broad; spikelets 50 to 240 per head or spike, 0.5-1 mm. broad, with 

 2 to 4 scales, straw-brown to dark-brown (to tawny-ochraceous).... 

 42. C ovularis. 



43. Achenes 1.3-1.7 mm. long; wings 0.8-1.4 mm. long; scales 1-1.3 mm. broad; 



spikelets 25 to 70 per head, with 3 to 8 scales, greenish-brown to 

 ochraceous-brown or olive 43. C globulosus. 



1. Cypenis lacvigatus L. Fig. 213. 



Densely tufted or mat-forming perennial; culms soft, 5-25 cm. long, 1-1.5 mm. 

 thick; leaves reduced to basal sheaths with subulate or setaceous blades 3-30 mm. 

 long; inflorescence 5-10 mm. long, of a single head of 4 to 8 spikelets; bracts 2, 

 the longer one 2-8 cm. long, appearing as a continuation of the culm; spikelet 

 straw-white or often white with atropurpurcous blotches medially, 4-7 mm. long, 

 2-3 mm. broad, 0.7-1 mm. thick, with 8 to 30 scales, the axis persistent, essen- 

 tially wingless, somewhat flattened; achene lenticular (often concavo-convex) with 

 one of the flat sides against the flattened spikelet axis. 



420 



