70 American Midland Naturalist Monograph No. 2 



1.5-2 mm. long; sandy soil, rare. Lake, Kankakee, and Sanga- 

 mon counties C. honghtonii Torr. 



7. Plants annual; spikelets 4-8 mm. long; stamen 1. 



9. Glumes long-acuminate, tapering to the recurved awn; wet sandy 

 soil along streams or ditches; plants fragrant when dry. [C. m- 

 flexus Muhl.} C. aristatus Rottb. 



9. Glumes merely acute; wet soil, chiefly in centr. and n. Ill 



C. acuminatns Torr. & Hook. 



1. Spikelets falling wholly away from the axis of the spikes, usually the 2 



lower glumes persistent; style 3-cleft; achenes trigonal. 



10. Plants perennial, with corm-like bases; spikelets more or less flattened. 



11. Spikelets 3-flowered; achenes 3-4 times as long as wide; inflore.scence 



composed of 5 or 6 globose heads; sandy borders of woods, or in 



old fields, chiefly in s. 111., but known also from Peoria Co. fC. 



woljii Wood} C. ovularis (Michx.) Torr. 



11. Spikelets 4-25-flowered. 



12. Leaves 4-6 mm. wide; achenes linear-oblong, acute; spikelets in 

 large umbels; moist meadows and alluvial soil near streams .... 



C. strigosiis L. 



12. Leaves 2-4 mm. wide; achenes obovoid, apiculate; inflorescence 

 consisting of 1-7 globose heads; dry sandy soil [C. filiculmis 



var. macilentus Fern.} C. filiculmis Vahl 



10. Plants annual; spikelets nearly terete. 



13. Glumes imbricated; achenes obovoid; wet ground, and sandy shores. 

 [C. specwsus of auth , not Vahl; C. jerax sensu Britt., not Rich.} 



C. ferruginescens Boeckl. 



13. Glumes scarcely overlapping; achenes linear-oblong; wet ground, 

 often on lake shores; Lake, McHenry, and Winnebago counties .... 

 C engclmanni Steud. 



2. Kyllingia Rottb. 



K. piimda Michx. Moist ground, chiefly along streams and ditches; s. 111., 

 extending northw. to Champaign Co. 



3. Dulichium Rich. 



D. arundinaceum (L.) Bntt. Wet ground, chiefly along borders of streams 

 and ponds, local. 



4. Eleocharis R. Br. — Spike Rush 



1. Spikelet linear, scarcely thicker than the stem; glumes of the mature spikelet 

 persistent; plants aquatic, about 1 m. tall. 

 2. Stems terete, conspicuously nodo,sv;; achenes 2-2.5 mm. long (including 

 the style-base); shallow water, n.w. 111. Wolf Lake, Hill in 1890. \E. 



intcrstincta sensu auth., non R. & S.} E. eqiinetoides (Ell.) Torr. 



2. Stems sharply 4-angled, continuous, not septate; achenes 2.5-4 mm. long, 

 including the beak (1 mm. long); shallow water, not common. Wolf 

 Lake, Hill; St. Clair Co., Brendcl. [E. mutata sensu auth., non R. &. 

 S.] E. quadrangulata (Michx.) R. & S. 



