310 American Midland Naturalist Monograph No. 7 



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



lent, 1-2 mm wide; dry ground, s. 111., rare 



S. paucifiora Muhl. 



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

 transversely wrinkled and reticulate; leaves glabrous, 1 mm or 

 less in width; moist meadows, locally in the northern half of the 

 state S. verticillata Muhl. 



14. Carex L. — Sedge 



ARTIFICIAL KEY TO GROUPS 



1 . Perigynia 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 emarginate, or 



if bidentulate the short teeth soft and thin group V 



6. Beak of the perigynium sharply bidentate group VI 



1. Perigynium more or less pubescent or puberulent; stigmas 3; achenes 

 trigonal group VII 



GROUP I 



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

 the staminate occurring at the apex; lateral spikes sessile; stigmas 2; 

 achenes lentictilar or plano-convex; perigynia glabrous. 



1. Stems arising singly from long rhizomes or prostrate old stems. 

 2. Inflorescence 1.5-6 cm long; leaves 2-4 mm wide. 



3. Perigynia ellipsoid, widest near the middle, 3-4 mm long, 1.5 

 mm wide, the beak 1-1.5 mm long; rhizomes long, stout, 

 black, fibrillosc; moist prairie soil, chiefly along railroads, 



in De Kalb and Winnebago counties 



- - C. prae gracilis W.Boott 



3. Perigynia lanceoloid, widest near the base, 2.5-3 mm long, 1-2 

 mm wide, the gradually tapering beak about 1 mm long; 

 rhizomes slender; marshes and bogs in the northern half 



of the state C. sartwellii Dewey 



2. Inflorescence subcapitate, 5-15 mm long; leaves involute, 0.5-1 

 mm wide; perigynia ellipsoid, 3 mm long, the beak 0.5-1 mm 

 long: old stems elongate, decumbent, producing new stems 

 from the leaf-axils; sphagnum bogs, Lake and McHenry 

 counties C. chordorrhiza L.f. 



