unit after the scales and achenes have fallen; scales laterally membranous and with 

 visible cells, medially chartaceous (eventually subcartilaginous), 1.5-2 mm. long, 

 in the proximal half to two thirds definitely bicarinate with a flat area or shallow 

 groove (0.3-0.5 mm. broad) dorsally (abaxially), the 2 lateral parts 0.6-0.7 mm. 

 broad (therefore the scale when spread out 1.5-1.9 mm. broad at the very base, 

 tapering all the way to the blunt apex), with 5 nerves (the midvein in the 

 channel between the keels inconspicuous) including a nerve at each keel and 

 one on each lateral face about a third the distance from the keel to the margin, 

 the whole scale as folded in position in the spikelet incurved slightly in the distal 

 half; stamen solitary; achene ovoid, 1.3-1.5 mm. long, 0.5-0.6 mm. thick, nearly 

 terete or obscurely triangular, slightly stipitate, apically acuminate and passing 

 imperceptibly into the style, black when mature but appearing dark-iridescent- 

 gray because of outer 1-cell thick covering of translucent cells; stigmas 3. 



Abundant in shallow water and mud, and edge of lakes and ponds, Rio 

 Grande Plains (n. to Bexar Co.) and s.e. Tex., throughout year, most profuse 

 Sept.-Nov.: C.A., W.I., Mex.. n. to Cuba and La. 



20. Cyperus pseudovegetus Steud. 



Tufted perennial, often slightly more loosely tufted than in C. virens by elonga- 

 tion of rhizomes 2-5 mm. between culms; culms 3-8 dm. long, erect basally 

 with a few leaves and 2-5 mm. thick, just beneath the inflorescence 1-2.2 mm. 

 thick, roundly triquetrous, smooth or rarely with microscopic antrorse scabrous- 

 ness; leaves few to several, the larger ones almost as long as the culms, basally 

 often with minute transverse septa between the close veins; inflorescence (ex- 

 cluding bracts) 2-9 cm. long, of 3 to 10 very unequal primary peduncles, the 

 shorter of which bear dense strongly 3- to 8-lobed glomerules or heads of 15 to 

 50 spikelets, the longer ones bearing some shorter unequal secondary peduncles 

 each with such a head; bracts 3 to 6, the longer ones far-surpassing the inflores- 

 cence; spikelets 2.5-4 mm. long, 2.3-3 mm. broad, narrowly ovate, blunt or 

 slightly acute, with 6 to 14 flowers, tawny stramineous to (very slightly reddish-) 

 brown, laterally compressed, the axis flat, wingless and persistent as a unit after 

 the scales and achenes have fallen; scales laterally membranous with visible cells, 

 medially firm to chartaceous, 1.8-2.5 mm. long, in the proximal fourth to third 

 the length bicarinate with a flat or shallowly groovelike area 0.1-0.2 (-0.3) mm. 

 broad dorsally (abaxially), the 2 lateral parts 0.2-0.4 mm. broad (therefore the 

 scale spread out is 0.6—0.7 mm. broad near the middle, almost linear), tapering 

 only at the very tip, with 5 inconspicuous nerves in the median portion, the whole 

 scale (as folded in the spikelet) incurved-falcate; stamen 1; achene linear, 1-1.3 

 mm. long, 0.2-0.3 mm. thick, bluntly trigonous, basally short-stipitate apically 

 acuminate, often slightly falcate, brown with a very thin translucent-iridescent 

 surficial layer of cells. C. arenicola Steud. 



Locally frequent in moist places, about lakes and ponds, in marshy areas and 

 seepage areas, in Okla. (Pushmataha, McCurtain, Pittsburgh, Atoka, Love and 

 LeFlore cos.), e. and s.e. Tex., infrequent in n.-cen. Tex., May-Sept.; Gulf States 

 and n. to N.J., Ind.. III., Mo. and Kan. 



Through error this species, in some works, has been called C. virens. 



21. Cyperus reflexus Vahl. 



Perennial with scaly creeping rhizomes 1-1.5 mm. thick; culms contiguous or 

 several mm. apart along the rhizome, 3-7 dm. long, erect, basally with a slightly 

 bulblike enlargement, with a few leaves and 1-2.5 mm. thick (just above the 

 "bulb"), just beneath the inflorescence 0.5-1.3 mm. thick, roundly triquetrous, 

 smooth; leaves few, the longer ones about as long as the culms or shorter, basally 

 not septate; inflorescence (excluding bracts) 15-50 mm. long, of 3 to 8 very 



443 



