312 American Midland Naturalist Monograph No. 7 



15. Perigynia ovate, truncate at base, 2 mm wide, the 

 beak 0.5 mm long, entire or nearly so; meadows 



and open woods, not common 



C. leavenworthii Dewey 



8. Leaves 4.5-8 mm wide; sheaths loose. 



16. Stem about 2 mm in diameter below the head, soft and 

 wing-angled, flattened when pressed and dry. 

 17. Beak of the perigynium about half the length of the 

 body, which is strongly nerved dorsally; sheaths 



rugose ventrally; woods and thickets, local 



C. conjuncta Boott 



17. Beak about as long as the body of the faintly nerved 



perigynium; sheaths not rugose; meadows, n. 111., 



not common C. alopecoidea Tuckerm. 



16. Stem 1 mm in diameter below the head, not winged. 



18. Inflorescence elongate, interrupted, 3-9 cm long; 



beak of the perigynium shorter than the body; 

 glumes acute; woods and thickets chiefly in the 

 northern half of the state ....C. sparganioides Muhl. 

 18. Inflorescence short, compact, 1-3 cm long. 



19. Beak of the perigynium equalling the body; 



glumes acute; woods and thickets 



C. cephaloidea Dewey 



19. Beak of the perigyniuin shorter than the body. 

 20. Glumes aristate, nearly as long as the peri- 

 gynia; river banks, meadows, edges of 

 woods, roadsides, common. [C lunelliana 



Mack.] C. gravida Bailey 



20. Glumes ovate, acuminate, shorter than the 



perigynia; woods and meadows, rare 



C. aggregata Mack. 



7. Spikes numerous (10 or more). 



21. Beak of the perigyniimi much shorter than the body. 



22. Leaves 5-8 mm wide; sheaths red-dotted; swamps, 



rare; Pulaski and Union counties 



C. decomposita Muhl. 



22. Leaves 2-4 mm wide; sheaths not red-dotted. 



23. Perigynia 2.5-3.5 mm long, 1.6-2.4 mm broad; 

 beak prominently notched; meadows, fields, 



pastures in the n. counties, not common 



C. annectcns Bickn. 



23. Perigynia 2.2-2.7 mm long, 1.5-1.8 mm broad; 

 beak obscurely notched; fields and pastures, oc- 

 casionally throughout 111 C. brachyglossa Mack. 



21. Beak equalling the body. 



24. Glumes awned; leaves 2-5 mm wide; swampy ground, 



often along ditches; common throughout 111 



C. vulpinoidea Michx. 



