42 CYPEKACEAE 



4. ELEOCHARIS E. Br. Spike Eush. 

 Culms terete or flattened, naked, terminated by the solitary spikelet. 

 Spikelet several-many-flowered with the scales imbricated in many ranks. 

 Perianth of from 3-12 downwardly barbed bristles. Stamens 2-3, styles 

 2-3-cleft, its bulbous base persistent on the achene as a tubercle. Achene 

 lenticular or three-angled. 



Achenes lenticular, smooth. 

 Annuals. 



Spikelets ovoid. 1. E. obtusa. 



Spikelets oblong-cylindrical. 2. E. Engelmanni. 



Perennials. 



Culms rather stout. 3. E. palustHs. 



Culms slender. 4. E. glaucescens. 



Achenes triangular, not smooth. 

 Culms 8'-2°' high. 



Culms flattened. 5. E. acuminata. 



Culms filiform. 6. E. tenuis. 



Culms l'-8' high, capillary. 7. E. acieularis. 



1. E. obtusa Sohultes. Annual vpith fibrous roots and terete culms : 

 spikelets 2"-5" long, ovoid or oblong, many-flowered : bristles 6-8, 

 longer than the achene : tubercle deltoid, acute and flat, narrower than 

 and one fourth the length of the achene. ^Common on muddy shores. 

 June-September. 



2. E. EDgelmanni Steud. Closely resembles the last but the culms 

 are stouter, the spikelets usually longer and oylindric. the six bristles are 

 not longer than the achene, and the tubercle covers the top of the achene. 

 — Well introduced in wet places in the first deep cut along the Missouri 

 Pacific Eailway, three-quarters of a mile south of the depot at Independ- 

 ence. Our form is the var. robusta Fernald. June-September. 



3. E. palustris (L.) E. & S. Culms terete or fiattened, l°-3° high, 

 from long creeping rootstooks : spikelets many-flowered, 2"-12''' long, 

 ovoid-cylindrical, thicker than the culms : scales usually brownish with 

 a scarious margin. — Common in wet places throughout. A frequent form 

 with flat culms is probably distinct. June. 



4. E. glaucescens Willd. Culms more slender than in the last : spike- 

 lets S'^-f)" long : achenes smaller and tubercles narrower. — Low grounds 

 along the Missouri Eiver near Courtney. June. 



5. B. acuminata (Muhl.) Nees. Culms compressed, slender, from 

 stout dark rootstooks: spikelets 2'''-5''' long, ovoid, thicker than the 

 culm : scales acute, lanceolate : achene 3-angled, dark colored, obovoid, 

 papillose, much longer than the depressed-oonio small tubercle. — Wet 

 prairies and barrens, Dodson, Lee's Summit. May-July. 



6. E. tenuis (Willd.) Schultes. Like the last but culms filiform and 

 scales obtuse.— Wet prairies. Independence, Lee's Summit. May-July. 



7. E. acieularis (L.) E. & S. Perennial: spikelets ovate or linear- 

 oblong, 3-many-flowered, wider than the culm : achene 3-angled, ribbed 



