oblique; spikelets broadly ovoid to nearly cylindric, of 50 to 100 flowers (50 to 80 

 in var. ohtusa, 60 to 100 in var. detonsa), obtuse; scales oblong to suborbicular, 

 firm, drab-stramineous with a narrow scarious margin, obtuse, falling promptly 

 in scries from bottom to top of spikelet; bristles several, varying from surpassing 

 the tubercle to essentially absent; style 2- to 3-branched; achenial body biconvex, 

 pyriform, 0.8-1.2 mm. long. 0.7-1 mm. broad, smooth and shiny, ripening through 

 shades of yellow-green to brown; tubercle forming a dark broad low-deltoid crown 

 on the body and in outline merging with it, not constricted basally, 0.1-4 mm. 

 long, 0.5-1 mm. broad (in var. ohtusa the tubercle 1.7 to 3 times broader than 

 long; in var. detonsa 2.8 to 4.5 times broader than long). E. Engehnannii Steud. 



Locally abundant in moist sandy soils, in wet meadows, shallow water of ponds 

 and edge of lakes, and mud of swamps, in Okla. (widespread), N.M. (Catron, 

 Eddy and Socorro cos.) and Ariz. (Apache and Coconino cos.), the var. ohtusa 

 in e. and s.e. Tex. passing into var. detonsa (Gray) Drapalik & Mohlenbrock in 

 n.-cen. Tex. and Edwards Plateau (Enchanted Rock area only), spring-summer; 

 o\er much of temp. N.A. [and perhaps including the Euras. £". ovata (Roth) 

 R. cSc S. as var. ovata (Roth) Drapalik & Mohlenbrock]. 



11. Eleocharis montana (H.B.K.) R. «fe S. 



Perennial, basally subrhizomatous but not extensive; culms densely tufted, 3-8 

 dm. long. 1.5-3.5 mm. thick, erect, terete, with complete septa 2-3 mm. apart; 

 sheaths basally reddish, apically lineolate. very firm, only very slightly oblique, 

 mucronate; spikelets lanceolate, 8-24 mm. long, acute, with 110 to 240 (to 350) 

 flowers; scales ovate and acute to broadly lanceolate, about 2 mm. long, medially 

 burty-brown and membranous, marginally hyaline and paler; bristles 6 to 8, brown- 

 ish, unequal, the longer ones about equaling the achenial body; style 2-branched 

 (in Texas material); achenial body 0.9-1.1 mm. long, obovate. biconvex (not 

 turgidly so), with 2 definite angles (in Texas material), ripening through shades 

 of pallid chartreuse and yellow to olive-brown, surficially punctulate-reticulate; 

 tubercle 0.1-0.2 mm. long, depressed-deltoid, about half as broad as the body 

 and scarcely restricted basally, almost merging with the body. 



Scarce in wet places, s.e. Tex. and s. as far as Nueces Co., N.M. (rather 

 widespread) and Ariz. (Pima and Pinal cos.), summer; widespread in S.A. and 

 C.A., W.I., n. to Ariz., N.M., Tex., La. and Fla. 



12. Eleocharis intersHncta (Vahl) R. & S. Fig. 191. 



Tufted perennial; culms 5-10 dm. long, 4-9 mm. thick, erect, essentially terete, 

 septate, the septa closer together as the spikelet is approached; sheaths often 

 tinged dark-red, apically firm, oblique; spikelets cylindric, 22-42 mm. long, 5-7 

 mm. thick, with SO to 140 flowers; scales (sub) cartilaginous, 3.5-5 mm. long and 

 broad, obtuse, rounded, stramineous to buffy-stramineous, marginally darker and 

 thinner, medially flat with a faint narrow midvein which is more heavily pig- 

 mented distally; bristles 6, exceeding the achene, brownish, stout, subcartilaginous, 

 flattened, with (usually rctrorse) serrulations; styles 2- or 3-branched; achene 

 body biconvex, 1.8-2.2 mm. long, brown (\ellow when immature), shiny; tubercle 

 high-conic, 1-1.2 mm. long, O.S mm. broad, dark, slightly constricted basally. 



Infrequent to rare in mud and in water on edge of streams, lakes and ponds, 

 in e. Tex., Rio Grande Plains and Edwards Plateau, probably elsewhere, summer- 

 fall; Fla.. Tex.. Berm.. W.l. s. to Bol. and Braz. 



13. Eleocharis eqiiisctoides (Fll.) Torr. Fig. 192. 



Tufted perennial, exceedingly similar to E. interstincta but the septa not as 

 crowded just below the spikelet and the bristles slightly shorter and thinner on 

 the average. 



378 



