316 American Midland Naturalist Monograph No. 7 



3. Glumes acuminate or acute, longer than the perigynia; stems 

 aphyllopodic. 

 6. Perigynia 2-2.5 mm long, turgid; moist ground in woods 



in the n. counties C. haydenii Dewey 



6. Perigynia 1.5-1.7 mm long, flattened; moist ground in 

 woods, rare C. emoryi Dewey 



GROUP IV 



Spike solitary, terminal, small, few-flowered, androgynous; peri- 

 gynia glabrous; stigmas three; achenes trigonal. 



1. Perigynia 2.5-3.5 mm long, beakless, ellipsoid; leaves 0.5-1.5 mm 

 wide; glumes obtuse; bogs and wet meadows .... C. leptalea Wahl. 



1. Perigynia 5-6 mm long, globose, with a roughened entire beak 3 

 mm long; leaves 2-3 mm wide; glumes aristate, foliaceous; dry 

 woods C. jamesii Schw. 



GROUP V 



Stigmas three; achenes trigonal; spikes two or more; perigynia gla- 

 brous, the beak (if present) small, entire, emarginate, or bidentulate. 



1. Leaves 1-3 cm wide; beak of the perigynium curved or bent. 



2. Cauline sheaths bladeless, red-tinged; woods, rare 



C. plantaginea Lam. 



2. Cauline sheaths with well developed blades. 



3. Perigynia sharply triangular; pistillate gkimes acute to acu- 

 minate. 

 4. Perigynia 5-6.5 mm long; rich woods, locally in eastern 



and southern 111 C. carcyana Torr. 



4. Perigynia 3-4.5 mm long; open woods, not common 



C. platyphylla Carey 



3. Perigynia obtusely triangrdar; pistillate glumes obtuse; woods, 



not vmcommon C. albursiyia Sheldon 



1. Leaves usually less than 1 cm wide. 



5. Leaves capillary, 0.5 mm wide; perigynia 2 mm long, minutely 

 straight-beaked or beakless; glumes obtuse; rocky soil, or 



sandy thickets, rare, in the northern half of 111 



C. eburnea Boott 



5. Leaves 1-9 mm wide. 



6. Perigynium beakless, or the straight beak not more than 0.5 

 mm long. 

 7. Mature perigynia conspicuously nerved or ribbed. 

 8. Spikes drooping on slender peduncles. 



9. Lateral spikes 3-6, linear-cylindrical, 2-3 mm thick; 

 perigynia twice the length of the obtuse glumes; 

 leaves 3-7 mm wide; moist woods and meadows, 

 common C. gracillima Schw, 



