Jones: Flora of Illinois, 23. Cyperaceae 75 



12. Cladium p. Br. — Twig-rush 

 (Mariscus Zinn) 



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

 jnd McHenry counties. 



13. ScLERiA Berg — Nut-rush 



l.Spikelets in terminal clusters; achenes supported by a basal disk (hypogyn- 

 ium). 

 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 n. half of the state, rare S. triglomerata Michx. 



2. Achenes papillose, subglobose, 1.5-2 mm. long; leaves puberulent, 1-2 



mm. wide; dry ground, s. 111.; Johnson Co., Brendel 



S. paitciflora Muhl. 



1 . Spikelets in an interrupted spike; hypogynium absent; achenes transversely 

 wrinkled and reticulate; leaves glabrous, 1 mm. or less in width; moist 

 meadows, Peoria, McDonald; Woodford Co., McDonald in 1887; Will 

 Co., Hill in 1911 S. yerticillata Muhl. 



Carex L. — Sedge 



KEY TO GROUPS 

 l.Pengynia glabrous. 



2. Stigmas two; achenes lenticular or plano-convex. 



3. Spikes of one kind, bearing both pistillate and staminate flowers; lateral spikes 

 sessile. 

 4. Spikes androgynous, i.e., with the staminate flowers at the apex Group I 



4. Spikes gynecandrous, i.e., with the staminate flowers at the base or middle of 

 the spike Group II 



3. Spikes usually of two kinds, the terminal commonly staminate, the lower entirely 

 or mostly pistillate Group III 



2. Stigmas three; achenes trigonal. 



5. Spike solitary, terminal, small, few-flowered, androgynous Group IV 



5. Spikes two or more. 



6. Beak of the perigynium (if present) small, entire or emargmate, or if bidenlu- 

 late the short teeth soft and thin Group V 



6. Beak of the perigynium sharply bidentate Group VI 



I.Perigynia more or less pubescent or puberulent; stigmas 3; achenes trigonal 



Group VII 



Group I 



Spikes of one kind, bearing both pistillate and staminate flowers; lateral 

 spikes sessile; stigmas 2; achenes lenticular or plano-convex. 



1 . Stems arising singly from long creeping rhizomes. 



2. Perigynia 3-5 mm. long, lanceoloid, strongly bidentate at apex: inflores- 

 cence nodding; leaves flat, 2-5 mm. wide; marshes and bogs in the n. 

 half of the state C. sartwellii Dewey 



2. Perigynia about 2 mm. long, ovoid, the apex entire; inflorescence stiff, 

 erect, subcapitate; leaves narrow, involute; bogs, rare; McHenry and 

 Lake counties C. chordorrhiza Ehrh. 



