80 American Midland Natliralist Monograph No. 2 



Group IV 



Spike solitary, terminal, small, few- flowered, androgynous; perigynia gla- 

 brous; 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 T. & G. 



Group V 



Stigmas three; achenes trigonal; spikes two or more; perigynia glabrous, the 

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

 present) soft and thin. 



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

 2. Perigynia sharply triangular, closely 30-50 nerved. 



3. Perigynia 2.5-3.5 mm. long; cauline sheaths blade-btaring, green; open 



woods, not common C. platyphylla Carey 



3. Perigynia 4-5 mm. long; cauline sheaths bladeless, ted-tinged; woods, 



rare C. plantaginea Lam. 



2. Perigynia obtusely triangular, tapering at the base, 3-4 mm. long, finely 

 nerved; woods, not uncommon C. albursitia Sheldon 



1. Leaves usually less than 1 cm. wide. 



4. Leaves capillary, 0.5 mm. wide; perigynia 2 mm. long, minutely straight- 

 beaked or beakless; glumes obtuse; rocky soil, or sandy thickets in the 



n. half of 111., rare C. eburnea Boott 



4. Leaves 1-9 mm. wide. 



5. Perigynium beakless, or the straight beak not more than 0.5 nim. long. 



6. Mature perigynia conspicuously nerved or ribbed. 

 7. Spikes drooping on slender peduncles. 



8. 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. graciUiina Schw. 



8. Lateral spikes 1-2, ellipsoid, 5-8 mm. thick; perigynia nearly 



equalling the acute or mucronate glumes; bogs, Peoria and 

 Tazewell counties, Brendel C. limosa L. 



7. Spikes ascending or erect. 



9. Terminal spike gynecandrous; leaves and base of stem more or 



less pubescent. 



10. Perigynia beakless, 2-3.5 mm. long; leaves 1.5-4 mm. wide. 



11. Perigynia 2-2.3 mm. long, ellipsoid, appressed or ascend- 

 ing, somewhat longer than or about equalling the 

 glumes; dry woods and meadows throughout 111. [C. 



triceps sensu auth., not Michx., or Schrank] 



C. hirsutella Mack. 



