|>ersistent wings on the spikelet axis which remains intact even after the scales and 

 achenes have fallen; stamens 3; the prominent long-exserted anthers with the con- 

 nective slightly prolonged into a minute reddish knob: achenes trigonous. 



Abundant in loamy soils, wet meadows and lawns, in Okla. (Waterfall), s.e., 

 n.-cen. Tex. and Rio Grande Plains, rare in Plains Country and Trans-Pecos, a 

 pernicious lawn-weed, adv. with us, July-Dec, less commonly Jan.-Apr.; wide- 

 spread in the warmer parts of the world, nat. to Euras. 



35. Cyperus setigenis T. & H. 



Perennial forming small colonies with creeping rhizomes (1-) 1.5-5 mm. 

 thick or slighly thicker at the culm bases; culms (60-) 75-110 cm. long, just 

 beneath the inflorescence (1.5-) 2.3-3.3 mm. thick; leaves few, attached in the 

 basal third of the culm, shorter than the culm, ascending; inflorescence (not in- 

 cluding bracts) (7-) 10-16 (-20) cm. long, of 9 to 13 extremely unequal peduncles 

 each bearing a compound cluster or short spike of divaricate spikelets, each cluster 

 or spike with 10 to 30 spikelets, the total inflorescence with 120 to 350 spikelets; 

 bracts about as many as the primary peduncles, the longer ones far-surpassing the 

 inflorescence; spikelets 6-40 mm. long, 1.5-2 mm. broad, laterally much-com- 

 pressed, with 6 to 40 flowers; scales keeled, reddish-brown, straight, 3-4 mm. long, 

 with 5 to 7 nerves either crowded medially or somewhat spread out so that each of 

 the halves is nerveless in the marginal fifth to three eighths the width, the sides 

 decurrent basally as hyaline persistent wings on the spikelets axis which remains 

 intact even after the scales and achenes have fallen; stamens 3; anther connective 

 sometimes minutely prolonged achenes trigonous. 



Scattered and local in moist clay meadows and ditches, about lakes and ponds 

 in Okla. (Comanche, Craig and Kay cos.), n.-cen. Tex., Rio Grande Plains, Ed- 

 wards Plateau (Mason Co.) and Plains Country, summer; Kan., Mo., Okla. and 

 Tex. 



36. Cyperus esculentus L. Yellow nut-grass. Fig. 234. 



Perennial forming colonies with creeping rhizomes 1-1.5 (-2) mm. thick (some 

 forms have tuberlike thickenings on the rhizomes; these forms rarely flower); culms 

 15-50 (-65) cm. long, just below the inflorescence 1.5-3 (-3.8) mm. thick; leaves 

 several, attached in the basal half of the culm, the upper ones ascending, almost 

 equaling or surpassing the inflorescence; inflorescence (not including bracts) 4-14 

 (-24) cm. long, of 5 to 10 extremely unequal peduncles each bearing a short spike 

 (or the longer peduncles a cluster of short spikes) of divaricate spikelets, each 

 spike or cluster with 12 to 50 spikelets, the total inflorescence with 70 to 350 

 spikelets; bracts about as many as the primary peduncles, the longer ones far- 

 surpassing the inflorescence; spikelets 6-30 mm. long, 1-2 mm. broad, somewhat 

 laterally compressed, with 8 to 40 flowers; scales keeled, straight, brown, buffy- 

 brown or golden-brown, 2.6-4 mm. long, hyaline, with 7 to 9 nerves which are 

 about equidistant and so spaced out that only about the marginal third of each 

 side of the scale is nerveless, the sides decurrent basally as hyaline persistent 

 wings on the spikelet axis which remains intact even after the scales and achenes 

 have fallen; stamens 3; anther connective prolonged into a red dot 0.05-0.1 mm. 

 long; achenes trigonous. Incl. var. angiistispicatus Britt. and var. macrostachyus 

 Boeckl. 



Locally abundant and weedy in occasionally moistened sandy usually disturbed 

 or unstable or loamy soil, in shallow water of ponds and lakes, gravel bars along 

 streams and on seepage banks, in Okla. (LeFlore, Ottawa, Pushmataha and Alfalfa 

 COS.), scattered all over Tex. but rare in Edwards Plateau and higher parts of the 

 Plains Country, N. M. (widespread) and Ariz. (Apache, Navajo and Coconino, 

 s. to Cochise, Santa Cruz and Pima cos.), summer-fall (through Dec. in extreme 



456 



