145. CVperaceae 309 



17. Spikclols subglobosc, 3-5 inin long; leaves 6-10 mm 

 wide; bristles at maturity much longer than the 

 glumes; wet ground, locally abundant, sometimes 

 covfM'ing large areas. [S. ruhricosus Fern.; S. pedicel- 

 Jatns Fern.] S. cyperinus (L.) Kvmth 



10. Eriophorum L. — Cotton Sedge 

 1. Glumes with 1 prominent midrib; spikelets 2-10; bristles bright 

 white; achenes 2-2.5 mm long; stamens 3; bogs, n.e. 111. {E. 

 gracile sensu 111. auth., non Koch; E. tenellum sensu auth. 



quoad pi. 111., non Nutt.] E. angustijolium Nutt. 



1. Glumes prominently 3-5-nerved; spikelets crowded into a head; 

 bristles tawny or copper-colored; achenes 3-3.5 mm long; sta- 

 men 1 ; tamarack bogs. Lake Co E. virginicum L. 



1 1 . Rhynchospora Vahl — Beaked-rush 

 1. Style entire or slightly 2-toothed, persistent as a long subulate beak 

 on the achene; bristles upwardly scabrellous; wet ground, rare, 



s. Ill R. cornicidata (Lam.) A.Gray 



L Style 2-cleft, only its base persistent as a tubercle on the achene. 

 2. Bristles downwardly barbed, or sometimes smooth. 



3. Glumes whitish; bristles 9-15; bogs; Lake Co., Gleason & 



Shobc 137; Peoria, Brendcl .'.... R. alba (L.) Vahl 



3. Glumes brown; bristles 6. 



4. Leaves filiform, less than 0.5 mm wide; spikelets 3-6 in a 

 terminal cluster; bogs and springy ground, n.e. 111., rare 



R. capillacea Torr. 



4. Leaves linear, 2-7 mm wide; spikelets numerous in clusters 

 or heads; lake shores, and moist ground, rare [inch R. 



glomcrata of auth., not (L.) Vahl] 



...R. capitellata (Michx.) Vahl 



2. Bristles upwardly barbed; leaves fiat, 1-4 mm wide; spikelets 

 ovoid, .sessile, in erect, cymose clusters; wet sandy soil, Kan- 

 kakee Co., Hill in 1871. [R. cymosa of auth.] 



R. globularis (Chapm.) Small 



12. Cladium P. Br. — Twig-rush 

 C. mariscoides (Muhl.) Torr. Bogs, marshes, or wet shores, Cook, 

 Lake, and McHenry counties. 



13. Scleria Berg. — Nut-rush 



1. Spikelets in terminal clusters; achenes supported by a basal disk 

 (hypogynium) . 

 2. Achenes smooth, ovoid, 3 mm long, the hypogynium covered 

 with a rough white crust; leaves glabrous, 3-9 mm wide; 



moist sandy .soil in the northern half of the state, rare 



S. triglomerata Michx. 



