ous to hyaline, the distal margin with slightly darker coloration; bristles about 6, 

 slender, unequal, some equaling the body, others surpassing the tubercle, with 

 minute retrorse serrulations; style 2- or 3-branched; achene body biconvex to 

 turgidly biconvex, 1.7-2.3 mm. long, brown (yellow when immature), shiny; 

 tubercle high-conic to deltoid or oblong, 1-1.5 mm. long, 0.8-1 mm. broad, 

 basally constricted, dark. 



Infrequent in mud and in shallow water at edge of ponds and lakes in Okla. 

 (Le Flore, Pushmataha, Muskogee, Ottawa, Latimer and Atoka cos.) and in e. 

 and s.e. Tex., rare in n. part of Rio Grande Plains, late spring-fall; most of e. 

 U.S., w. to Wise, Mo., Okla. and Tex.; also Jal. 



7. Eleocharis fistulosa (Poir.) Schult. 



Tufted perennial, apparently rather similar to E. quadrangulata but the culms 

 sharply triangular and the spikelets and scales averaging slightly smaller; achene 

 body 1.4-1.7 mm. long; tubercle 0.7-1 mm. long. 



Rare in Tex., Rio Grande Plains, summer-fall (?); widely distributed in the 

 warmer parts of the world, in Am. n. to Cuba and Tex. 



8. Eleocharis melanocarpa Torr. Fig. 189. 



Densely tufted perennial; culms 2-6 dm. long, flattened, about 1 mm. thick 

 in the larger dimension, on each side paucicostate and paucisulcate; sheaths 

 apically firm and thickened, mucronate; spikelets narrowly ovoid, obtuse, 6-12 

 mm. long, 4-5 mm. thick, with 20 to 40 flowers; scales ovate, 3-3.5 mm. long, 

 with a pale buffy very firm midrib, passing laterally through firm-brown to 

 membranous-stramineous marginally; bristles dark-brown, shorter than the 

 achene tubercle, retrorsely toothed or much-reduced; style 3-branched; achenial 

 body obpyramidal-trigonous, 0.8-1 mm. long, apically truncate, ripening through 

 fuscous to black, glossy; tubercle paler, caplike, 0.3-0.5 mm. long, 0.8-1 mm. 

 broad, often broader than the body and overhanging its truncate apex, depressed 

 centrally with a slight pointed umbo. 



Rare in moist sandy often boggy loam, e. Tex. (Leon and Upshur cos.), 

 summer-fall (?); Coastal States, Mass. to Tex.; also Ind. and Mich. 



Plants of this species appear to combine some characters of E. rostellata and 

 some of E. obtusa. 



9. Eleocharis lanceolata Fern. 



Densely tufted annual; culms 1-2 dm. long, 0.3-0.9 mm. thick, erect; sheaths 

 apically firm and oblique; spikelets lanceolate to lance-ovoid, of 30 to 80 flowers, 

 acute; scales ovate, firm, brownish-stramineous, with a narrow scarious margin, 

 acute, falling promptly in series from bottom to top of spikelet; bristles 6 or 7, 

 usually surpassing the tubercle; style 2- or 3-branched; achenial body 0.9-1.1 

 mm. long, 0.7-0.8 mm. broad, biconvex, pyriform in outline, smooth, shiny, 

 ripening to a brownish color; tubercle forming a dark broad low-deltoid crown 

 on the body and in outline merging with it, not constricted basally, about 0.4 mm. 

 long, 0.5-0.6 mm. broad. E. obtusa var. lanceolata (Fern.) Gilly. 



In moist or wet loamy soils and muddy margins of ponds and lakes, in Okla. 

 (Mcintosh, Pittsburg. McCurtain, Atoka and Ottawa cos.) and in n.-cen. and 

 n.e. Tex. (Grayson and Bowie cos.), summer-fall (?); Mo., Kan., Ark., Okla. and 

 Tex. 



10. Eleocharis obtusa (Willd.) Schult. Fig. 190. 



Densely tufted annual (rarely persisting more than 1 season); culms 3-50 cm. 

 long, 0.3-1.6 mm. thick (fleshy and sometimes seemingly broader when pressed 

 flat), erect, striate; sheaths often slightly purplish basally, apically firm and 



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