304 American Midland Naturalist Monograph No. 7 



17. Plants perennial; scales stramineous; 

 achenes linear, 1.3-2.2 mm long; 

 moist meadows and alluvial soil, com- 

 mon. Aug.-Oct C. strigosus L. 



2. Dulichium Rich. 



D. arundinaccum (L.) Britt. Wet ground, chiefly along borders of 

 streams and ponds, local. 



3. Eleocharis R. Br. — Spike Rush 



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

 mature spikelet persistent; plants acjuatic, about 1 m tall. 



2. Stems terete, conspicuously nodose; achenes 2-2.5 mm long (in- 

 cluding the style-base) ; shallow water, rare, n.e. 111. Wolf 

 Lake, Hill in 1890. [E. intcrstincta sensu auth., non R. & S.] 

 E. equisetoides (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., Brcndel. [E. 



mutata sensu auth., non R. & S.] 



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



1. Spikelet usually much thicker than the stem; glumes persistent. 



3. Style 2-cleft; achenes lenticular or biconvex. 

 4. Perennials with rhizomes. 



5. Sheaths loose, hyaline and scarious at the summit; glumes 

 hyaline-margined; wet soil, rare. Wolf Lake, Chicago, 



Hill, and other localities E. olivacea Torr. 



5. Sheaths close, not hyaline at the summit. 



6. Basal glumes of the spikelets usually 2 or 3 below the 



thinner fertile glumes. 



7. Tubercle elongate, much longer than broad; achenes 



narrowly obovoid or pyriform; stems subterete, 



rather firm; ponds, swamps, and marshes, n. 111. 



Creeping Spike Rush E. palustris (L.) R. & S. 



7. Tubercle depressed-deltoid, umbonate, as broad as or 



broader than long; achenes broadly obovoid or 



roimdish. 



8. Stems firm, nearly terete; fertile glumes ascending, 



oval, acuminate; marshes, ditches, shores, locally 



throughout 111 E. smallii Britt. 



8. Stems soft, compressed; fertile glumes appressed, 

 obtusish; wet ground, not common; chiefly in the 

 southern half of the state, extending northward 



to Menard Co E. mamillata Lindb. 



6. Basal glume solitary, spathiform, usually encircling the 



base of the spikelet; wet ground, local E. calva Torr. 



4. Tufted annuals, with fibrous roots. 



