145. Cyperaceae 305 



9. Tubercle flattened or saucer-shaped; mature achenes black, 

 1 mm long; wet ground. [E. capitata R.Br.; E. caribaea 



(Rottb.) Blake; E. dispar E.J.Hill] 



E. gtniculata (L.) R. & S. 



9. Tubercle conical or deltoid, acute; mature achenes pale 

 brownish. 



10. Tubercle conical, narrower than the top of the achene; 

 wet ground in the northern half of the state 



E. ovata (Roth) R. & S. 



10. Tubercle depressed-deltoid, as wide as the top of the 

 achene. 



11. Bristles longer than the achene; tubercle one-third 

 or more the length of the body of the achene; 

 spikelets ovoid ; wet ground throughout 111., not 



uncommon. Blunt Spike Rush 



E. obtusa (Willd.) Schult. 



11. Bristles about equalling the achene, or rudimentary; 

 tubercle less than one-fourth the lensrth of the 

 body of the achene; spikelets cylindrical-ellipsoid; 

 muddy shores and along ditches, local. Engel- 



mann's Spike Rush E. engelmanni Steud. 



3. Style usually 3-cleft; achenes trigonal or turgid. 



12. Tubercle plainly distinguishable from the achene; achenes 

 less than 2 mm long. 



13. Achenes cancellate and striate. 



14. Spikelet flattened, 3-9-flowered, the glumes 2-3- 

 ranked; bristles 3-4, fugacious; stems very slender, 

 not more than 0.5 mm in diameter, 5-20 cm long; 

 wet ground and shallow water. Needle Spike Rush 

 - E. acicularis (L.) R. & S. 



14. Spikelet terete, the glumes many-ranked; bristles 0; 



stems about 1 mm in diameter; wet ground; Ful- 

 ton, Peoria, Stark, and La Salle counties. Discov- 

 ered at Canton by J. Wolf 



E. wolfii (A.Gray) Patterson 



13. Achenes papillose or pitted. 



15. Tubercle depressed; achene about 1 mm long; peren- 



nials with rhizomes. 



16. Stems filiform, about 0.5 mm wide, angular; 

 glumes obtuse; wet ground, local. [E. clliptica 

 Kunth; E. capitata var. borealis Svens.] Slen- 

 der Spike Rush E. tenuis (Willd.) Schult. 



16. Stem flattened, 1 mm or more in width; glumes 

 acuminate, often bifid; moist ground tlirough- 



out 111. [E. acuminata (Muhl.) NeesJ 



E. compressa Sulliv. 



