scale when spread out 0.9-1.2 mm. broad, ovate), rounded or slightly acute, with 

 3 nerves (the inconspicuous midnerve plus the 2 prominent laterals which form 

 the proximal keels); dorsum of the scale as it is folded in position in the spikelet 

 gently incurved in the proximal part, nearly straight distally; stamen 1; achene 

 elliptic-oblong or oblong, 0.7-0.8 mm. long, 0.25-0.3 mm. thick, bluntly trigo- 

 nous, dark-rosy-brown, basally minutely stipltate, apiculate or shortly acuminate. 

 Infrequent in moist places, wet meadows and pastures, s.e. Tex. and coastal 

 parts of Rio Grande Plains, rare in n.-cen. and e. Tex., July-Nov., rarely spring; 

 Arg. and Bol. n. to Fla., La. and Tex. 



18. Cypenis virens Michx. Fig. 226. 



Tufted perennial; culms 5-1 1 dm. long, erect, basally leafy and 5-12 mm. thick, 

 just beneath the inflorescence 3-8 mm. thick, sharply triquetrous and often with 

 microscopic rigid antrorse projections like shark's teeth especially on the angles; 

 leaves several, the longer ones almost as long as the culm, basally usually with 

 numerous short incomplete transverse septa visible after pressing and drying; in- 

 florescence (excluding bracts) 3-13 cm. long, of 6 to 14 very unequal primary 

 peduncles, the shorter of which bear nearly spherical heads of 12 to 30 spikelets, 

 the longer ones bearing some shorter unequal secondary peduncles each with a 

 head of 16 to 40 spikelets; bracts 5 to 9, the longer ones far-surpassing the 

 inflorescence; spikelets 6-13 mm. long, 2.5-3.3 broad, linear, acute, with 10 to 

 36 flowers, stramineous (young) to olive-brown or grayish-brown (mature), 

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

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

 medially chartaceous (to eventually subcartilaginous), 2-2.4 mm. long, in the 

 proximal third to five eighths the length definitely bicarinate with a flat area or 

 shallow groove 0.25-0.4 mm. broad dorsally (abaxially), the 2 lateral parts 

 0.5-0.6 mm. broad (therefore the scale spread out 1.2-1.5 mm. broad just below 

 the middle), in the lower half linear, gently tapering distally, with 5 nerves (1 of 

 these being the inconspicuous midvein between the keels), including 1 nerve at 

 each keel and 1 on each lateral face about a fourth to a third the distance from 

 the keel to the margin, the whole scale (as folded in the spikelet) incurved slightly 

 in the distal half; stamen 1 ; achene linear, triquetrous, basally stipitate. apically 

 acuminate, 1-1.5 mm. long, 0.3-0.5 mm. thick, brownish with a very thin trans- 

 lucent surficial layer of cells. 



Abundant in moist places, in shallow water and on edge of streams, ponds and 

 lakes, in Okla. (McCurtain, Sequoyah, Muskogee, LeFlore and Osage cos.) and 

 s.e. Tex., frequent in e. Tex. and coastal parts of Rio Grande Plains, May-Oct.; 

 Urug. and Ecu. n. to N.C. and the Gulf States, adv. in Calif. 



Through error, the name C virens has been widely misapplied to C. pseudo- 

 vegetus. The 2 taxa are extremely closely related and occasionally hybridize. 

 Young specimens of C. virens greatly resemble C. pseudovegetus. 



19. Cyperus ochraceus Vahl. Fig. 227. 



Perennial, tufted; culms 11-80 cm. long, basally 2-5 mm. thick, apically 

 bluntly trigonous, 1-2.7 mm. thick, erect, smooth; leaves several, basally aggre- 

 gated, the longer ones about as long as the culm, not septate-nodulose; inflores- 

 cence (excluding bracts) 25-185 mm. long, of 6 to 12 very unequal primary 

 peduncles, the shorter of which bear nearly spherical lax heads of 4 to 15 spike- 

 lets, the longer ones bearing some short unequal secondary peduncles each with 

 a head of 4 to 24 spikelets; bracts 5 to 8. the longer ones far-surpassing the 

 inflorescence; spikelets 5-20 mm. long, 2-2.5 (-3) mm. broad, linear, acute, with 

 10 to 30 (to 40) flowers, olive-stramineous (young) to olive-yellow or yellowish- 

 brown (mature), laterally compressed, the axis flat, wingless and persistent as a 



441 



