long and 0.2-0.3 mm. broad; stamens 3; connective of anthers not surpassing the 

 anther cells themselves or else projected as a red point only 0.05-0.1 mm. long; 

 achene unequally trigonous. 



Abundant in marshy places, sand flats and in shallow water of lakes and ponds, 

 along creeks, in Okla. (widespread), s.e. Tex., infrequent in Rio Grande Plains, 

 n.-cen. and e. Tex., probably elsewhere, N. M. (Dona Ana Co.) and Ariz. 

 (Coconino, Mohave and Yuma cos.), July-Dec; Ont. and e. U.S. w. to N.D., 

 S.D., Neb., Kan., Okla. and N.M.; also Wash., Ore., Calif., Ariz, and Ut.; pre- 

 sumably also Tam. 



Probably not sufficiently distinct from C. digitatus. 



27. Cyperus digitatus Roxb. 



Tufted perennial; culms 5-15 dm. long; inflorescence an umbel-like aggregation 

 of 5 to 13 long markedly unequal peduncles each bearing an irregular cluster of 

 several nearly sessile spikes with elongate axes (internodes of spike axis 0.6-2 

 mm. long) and 15 to 35 spreading spikelets; spikelets about 1 mm. broad, laterally 

 compressed, 7-15 mm. long, with 8 to 35 flowers; bracts of umbel about as many 

 as peduncles and some as long as or longer than the inflorescence; bracts of spike 

 clusters considerably reduced, inconspicuous; spikelet axes persistent as units 

 after the achenes and scales have fallen; scales keeled, the lower sides decurrent 

 down the spikelet axis as readily deciduous hyaline wings 0.2-0.3 mm. broad and 

 about 0.8 mm. long; stamens 3; connective of anther not surpassing the anther 

 cells themselves or else merely a red point 0.05-0.1 mm. long; achene unequally 

 trigonous. 



Local in marshy places near Brownsville, Laredo and Corpus Christi in Rio 

 Grande Plains, July-Dec; Braz., Col., Mex., W.L and Tex. 



28. Cyperus onerosus M. C. Johnst. 



Perennial with scaly rhizomes 5-80 mm. long and 1-2 mm. thick; culms 

 20-49 cm. long, erect, basally leafy and 2-4 mm. thick, just beneath the in- 

 florescence smooth, sharply triquetrous and 1.5-2 mm. thick; leaves few, basally 

 with no transverse septation, some of the longer ones usually surpassing the 

 inflorescence; inflorescence (excluding bracts) 2-12 cm. long, with 7 to 15 very 

 unequal primary peduncles, the shorter of these bearing nearly spherical heads of 

 8 to 25 spikelets, the longer ones bearing 3 to 12 unequal secondary peduncles 

 each bearing a head of 20 to 35 spikelets; bracts about 4, the longer one nearly 

 erect, exceeding the inflorescence; spikelets 7-13 mm. long, 2.5-3.5 mm. broad, 

 linear, with (10 to) 16 to 26 (to 42) flowers, brownish to tawny-brown, laterally 

 compressed; the axis wingless, thick, dorsiventrally slightly flattened, persistent as 

 a unit after the scales and achenes have fallen, the internodes sculptured (with a 

 niche for each achene); scales 2.3-2.9 mm. long, 1.2-1.4 mm. broad, ovate- 

 elliptic when unfolded, basally slightly gibbous, laterally firm-membranous, 

 medially chartaceous and with a midnerve and on each side 2 (rarely 3) nerves 

 (the total number obscure except when the scale is young and translucent), the 

 medial nerved keel-like zone (as seen in place in the spikelet) except for the 

 curve at the gibbous base mostly straight or very slightly excurved to the very 

 acute apex; stamens 3; achene elliptic to narrowly so, trigonous, acuminate at 

 both ends, 0.7-0.8 mm. long, 0.25-0.3 mm. thick, whitish or eventually turning 

 brownish. 



Locally frequent in moist or wet loose sand and pools between sand dunes, s.w. 

 part of Plains Country of Tex. (Ward and Winkler cos.), June-Nov.; endemic. 



29. Cyperus compressus L. Fig. 230. 



Tufted annual (or occasionally appearing as a short-lived perennial); leaves 

 few, clustered near the base, little shorter than the culms; inflorescence (not 



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