76 American Midland Naturalist Monograph No. 2 



1. Stems tufted. 



3. Perigynia subulate-lanceolate. 



4. Perigynia 4 mm. long, the beak about the length of the body; swamps 



and wet meadows C. stipata Muhl. 



4. Perigynia 5-7 mm. long. 



5. Perigynium about 5 mm. long, tapering gradually from base to apex; 

 inflorescence 2.5-6 cm. long; leaves 3-6 mm. wide; swampy woods 



C. laevivaginata (Kiikenth.) Mack. 



5. Perigynium 6-7 mm. long, abruptly enlarged below into a disc-like 

 base; inflorescence 7-17 cm. long; leaves 5-10 mm. wide; swampy 



ground C. cruscorvi Shuttlw. 



3. Perigynia oval, ovate-lanceolate, ovoid or ellipsoid. 



6. Spikes usually fewer than 12; inflorescence often capitate. 

 7. Leaves 1-4 mm. wide; sheaths close. 



8. Perigynia spongy-thickened at the base. 



9. Perigynium with a minute beak 0.2 mm. or less in length; bogs, 



n.e. Ill C. dispertna Dewey 



9. Perigynium with a distinct beak 0.6-1 mm. long. 



10. Beak entire-margined; glumes acuminate or cuspidate. 



1 1 . Body of the perigynium broadly ovate, deep green, 



abruptly short-beaked; dry woods, not common 



C. retro flexa Muhl. 



1 1 . Body of the perigynium ovate-lanceolate, light green, 



tapering to the beak; dry woods, s. 111.; (fide Macken- 

 zie; no 111. spec, seen) C. texensis (Torr.) Bailey 



10. Beak minutely serrulate along the edges. 



12. Broadest leaves 1-2 mm. wide; perigynium tapering into 



the beak; stigmas long, slender, usually not twisted; 

 woods and thickets, common C. rosea Schk. 



12. Broadest leaves 2-3 mm. wide; perigynium abruptly con- 

 tracted into the beak; stigmas short, stout, contorted, 

 red; dry woods, common C. convoluta Mack. 



8. Perigynia not spongy-thickened at the base. 



13. Heads mostly 1.5-3.5 cm. long; leaves and stems stiff and wiry; 

 perigynia oval, 3-3.5 mm. long, 2.5 mm. wide, the beak 0.5 

 mm. long, serrulate; sandy soil, often in open woods, in the 

 n. half of III. [C. plana Mack.] C. niuhlenbergii Schk. 



13. Heads mostly 8-15 mm. long; leaves and stems soft; perigynia 

 2.5-3 mm. long. 

 14. Perigynia oval, 1-1.5 mm. wide, the serrulate beak 1 mm. 



long; open woods or along roads, frequent 



C. cephalophora Muhl. 



14. Perigynia ovate, truncate at base, 2 mm. wide, the beak 0.5 

 mm. long, entire or nearly so; meadows and open woods, 



not common. Jackson Co., French in 1905 



C. leavcnworthn Dewey 



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



