Jones: Flora of Illinois, 23. Cyperaceae 83 



4. Leaves 3-5 mm. wide; perigynia 10-12 mm. long, the beak smooth, 

 not serrulate; pistillate spikes subglobose-ellipsoid, 2-3.5 cm. long; 

 staminate spike 2-2.5 mm. wide; stems solitary or few from elon- 

 gate rhizomes; achenes longer than wide, the angles not promi- 

 nently thickened; wet ground in woods, s. 111. [C. halei sensu 

 Carey, non Dewey] C. louisianica Bailey 



4. Leaves 5-15 mm. wide; perigynia 13-20 mm. long; pistillate spikes 

 ellipsoid-cylindrical, 2-8 cm. long; staminate spike 3-5 mm. wide; 

 stems cespitose. 



5. Beak of the perigynium serrulate; achenes longer than wide, the 

 angles not thickened; swamps, common C. lupuUna Muhl. 



5. Beak of the perigynium smooth; achenes as wide as long, the an- 

 gles prominently thickened; wet ground, local 



C. lupuliformis Sartw. 



2. Mature perigynia not more than 1 cm. long. 



6. Leaves involute-filiform; pistillate spikes 1 or 2, sessile, globose, few- 

 flowered; perigynia ovoid, turgid, glossy, 4-7 mm. long, nearly twice 



the length of the obtuse glumes; bogs. Lake Co. Htll in 1908 



C. oligosperma Michx. 



6. Leaves flat. 



7. Perigynia obovoid, 4-5 mm. long, truncate above and abruptly subu- 

 late-beaked; terminal spike often mostly pistillate. 



8. Perigynia shorter than the serrulate, linear-subulate glumes; ditches 



and swamps, extending northw. to McLean Co 



C. frankii Kunth 



8. Perigynia much longer than the glumes. 



9. Perigynia squarrose; glumes acute to mucronate; style strongly 

 curved near the ovary; swampy ground and roadside ditches, 

 common C. squarrosa L. 



9. Perigynia ascending; glumes obtusish or acutish; style straight 

 throughout; swamps and roadside ditches, chiefly in the s. 

 half of III., but extending northw. to Macon Co. [C. typhi- 

 noides Schw.} C. typhina Michx. 



7. Perigynia lanceoloid, ellipsoid, or ovoid, more or less tapering into 

 the beak. 



10. Glumes with a serrulate awn. 



11. Perigynia lanceoloid, strongly ribbed, soon reflexed. 



12. Teeth of the perigynium erect or slightly spreading, 0.5- 

 1 mm. long; perigynium 4-5 mm. long, the beak shorter 

 than the body; bogs and swamps, Kane and Du Page 

 counties C. pseudocyperus L. 



12. Teeth strongly divergent, 1-2 mm. long; perigynium 5-7 

 mm. long, the beak equalling or exceeding the body; 



swamps and ditches C. comosa Boott 



11. Perigynia ellipsoid or ovoid, often inflated, 5-9 mm. long. 



