CYPERACEAE. 43 



spikelets solitary or clustered, 1 to many-flowered; scales two- 

 ranked or in a spiral, persistent or deciduous; perianth hypogy- 

 nous, of bristles, or interior scales wanting; stamens 1-3, rarely 

 more; ovary 1-celled, 1-ovuled; style 2- or 3-cleft; fruit a lenticular 

 or three-sided akene; endosperm mealy; embryo minute. 



Flowers monoecious or dioecious, usually borne in 



separate spikes. 65. Carex, 43. 



Flowers of the spikelet all, or at least one of them 

 perfect; spikelets all similar. 

 Spikelets compressed; scales 2-ranked. 66. Cyperus, 49. 



Spikelets not compressed; scales in a spiral. 



Base of style swollen, persistent as a tubercle on 



the akene. 67. Eleocharis, 50. 



Base of style not swollen, deciduous or per- 

 sistent as a subulate tip. 

 Bristles present; hyaline scales none. 68. Scirpus, 51. 



Bristles none; perianth of a single minute 



posterior scale. 69. Hemicarpha, 52. 



65. CAREX. Sedge. 



Grass-like sedges, perennial by rootstocks; stems mostly 

 triangular; leaves 3-ranked, the upper (bracts) elongated or very 

 short, and subtending the spikes of flowers, or wanting; flowers 

 solitary in the axils of bracts (scales), monoecious or dioecious; 

 spikes either wholly staminate, or pistillate, or sometimes 

 androgynous; perianth none; staminate flowers of 3 stamens; 

 pistillate flower of a single pistil with a style and 2-3 stigmas 

 borne in the axil of a second bract (the perigynium) which com- 

 pletely encloses the akene; akene 3-angled, lenticular or plano- 

 convex. 



Section 1. Spikes sessile, all alike, bearing the inconspicuous staminate 

 flowers either at the base, at the top, or rarely scattered; stigmas 2; akenes 

 lenticular. Subgenus Vignea. 



Spikes not densely aggregated, the individual ones easily dis- 

 tinguished. 

 Perigynia wing-margined. 



Perigynia 6-7 mm. long; spikes acute. C. liddoni. 



Perigynia 3—4 mm. long; spikes obtuse. 



Bract present; perigynia twice as long as broad. C. bebbii. 

 Bract wanting; perigynia as broad as long. C. festucacea. 



Perigynia not wing-margined. 



Spikes 10-30-flowered; perigynia straight. C. bolanderi. 



Spikes 4-8-flowered; perigynia curved. C. laeviculmis. 



Spikes densely aggregated, the individual ones, at least the 

 uppermost, distinguishable with difficulty. 

 Perigynia margined. 



Dioecious or with the staminate and pistillate flowers 

 irregularly scattered. 



