75(74). Perigynia in transection flattened-triangular to unequally biconvex, 

 2.3-2.8 mm. long, ascending 71. C. complanata. 



15. Perigynia in transection nearly round, 1.8-2.3 mm. long, spreading 



72. C caroliniana. 



76(63). Perigynia ascending or not strongly divergent; the orifice entire, oblique 

 or but slightly notched (77) 



76. Perigynia usually soon divergent, many-ribbed, 2-3 mm. long, the beak one- 

 third as long as the body; beak minutely bidentate 



73. C. viridula. 



71(76). Terminal spike regularly pistillate except at base 74. C. oxylepis. 



11 . Terminal spike regularly staminate throughout (78) 



IS(ll). Culms from lateral buds or sometimes central, relatively weak, readily 

 compressed, soon shriveling after maturity of fruit; perigynia ellip- 



soid-obovoid, 3-4.5 mm. long, strongly asymmetrical 



75. C. hianda. 



78. Culms from centers of leafy tufts, slender and firm, not easily compressed, 



long-persistent after falling of fruit (79) 



79(78). Pistillate spikes linear- to oblong-cylindric, the lower peduncled and 

 usually drooping or loosely spreading; perigynia lanceolate to fusi- 

 form or ovoid (80) 



79. Pistillate spikes oblong-cylindric, erect or ascending, only rarely with elon- 



gated peduncles; perigynia ellipsoid to oblong-ovoid or subglobose 

 (81) 



80(79). Bases purple or purplish; lowest sheaths at base of culm without green 



blades; perigynia fusiform-lanceolate, 4-10 mm. long 



76. C. dehiUs. 



80. Bases drab or brown; lowest sheaths at base of culms with elongate green 



blades; perigynia lance-ovoid, subfusiform, 2-3 mm. long 



77. C. cupilloris. 



81 (79) . Perigynia with elevated ribs, 2-3.6 mm. long (82) 



81. Perigynia with impressed nerves, 4-6 mm. long (84) 



82(81). Plant cespitose with several culms from a crown; leaves flat, flaccid; 

 staminate spikes sessile or short-peduncled 78. C. granulans. 



82. Plant loosely stolonifcrous with culms solitary; leaves often folded, firm; 



staminate spike long-peduncled (83) 



83(82). Pistillate spikes 4-6 mm. thick; perigynia 3-3.5 mm. long, many-nerved, 

 with minute hyaline-tipped beak 79. C. Crawei. 



83. Pistillate spikes 7.5 mm. thick; perigynia 3-4.5 mm. long, definitely ribbed, 



the beak strongly bidentate 80. C. microdonta. 



84(81). Leaves thin and flaccid to firm, green, rarely glaucous, 1.5-4 mm. 

 wide; lower spike 8-13 (-20) mm. long, with 3 to 6 (to 10) 

 perigynia 81. C. amphihola. 



84. Leaves firm to coriaceous, usually glaucous, 4-10 mm. wide; lower spike 



12-50 mm. long, with 8 to 32 perigynia 82. C. ffaccospcrnia. 



1. Carex Doiiglasii Boott. Fig. 255. 



Rhizomes 1-2 mm. thick, tough; culms 6-30 cm. tall, slender but stiff, obtusely 

 triangular, smooth, usually overtopping the leaves but sometimes shorter; leaves 

 clustered near the base, 5-15 cm. long, 1-2.5 mm. wide, involute above and flat 

 or channeled toward base; heads usually dioecious, the many spikes closely aggre- 

 gated but usually distinguishable; pistillate heads suborbicular to oblong. 1.5-5 

 cm. long, 1-2.5 cm. thick; scales yellowish-brown with broad hyaline margins and 



496 



