Sandy sloughs in prairie provinces, particularly in w. Kan. and Neb. but ex- 

 tending s. into w. Tex. and southw. to Ariz. 



8. Hemicarpha Nees & Arn. 



A genus of a few species (perhaps as many as 6) of warm regions. Hemicarpha 

 is closely related to Cyperus subgenus Kyllinga but the inflorescence and flowers 

 are much-reduced. Some authors include Hemicarpha in Scirpus but this has 

 very little merit. 



1. Hemicarpha micrantha (Vahl) Britt. Fig. 212. 



Essentially glabrous densely tufted annuals; culms 1-22 cm. long, 0.2-0.6 mm. 

 thick, essentially leafless; leaves usually 2 per culm at its base; upper sheath 

 purplish or brownish, its blade linear to setaceous; lower sheath much-reduced, 

 its blade absent; lower bract often appearing as a continuation of the culm, 7-37 

 mm. long; 1 or 2 other much-reduced bracts present; inflorescence a glomerule of 

 2 (rarely 3) sessile heads or head solitary; heads broadly ovoid, 2-8 mm. long, 

 of 60 to 140 uniflorus spikelets in tight spirals; scale solitary per spikelet,e()?t,d 

 of 60 to 140 uniflorus spikelets arranged in tight spirals; scale solitary per spikelet, 

 abaxial, ovate to lanceolate, 0.8-2.3 mm. long, the midrib conspicuous often as 

 a keel in the lower part and a mucro or awn apically, the sides membranous, 

 convex; "perianth" (actually the wings of the reduced spikelet axis) of a single 

 hyaline adaxial scale, often split and torn by or adhering to the achene, very 

 inconspicuous; stamens 1 or 2; styles 2-branched; achene oblong, nearly terete 

 or elliptic in transection, 0.5-0.8 mm. long, very minutely apiculate, surficially 

 miscroscopically papillate. Scirpus micranthus Vahl. 



The species is widespread in wet or moist soils in warm temp, and trop. areas 

 of Am. We have 3 varieties as follows: 



Var. micrantha. "Perianth" scale much shorter than the achene, often bifid 

 or reduced or absent. Infrequent or rare in moist or wet soils along streams, s, 

 part of e. Tex., Rio Grande Plains and Trans-Pecos; widespread in trop. Am., 

 Calif., Wash.. Gulf States and n.e. U.S. 



Var. aristulata Cov. "Perianth" scale equaling or surpassing the achene and 

 often cupped around it distally and adaxially, with no definite vascular tissue 

 (use magnification of 40 diameters); awn of floral scale two thirds as long as 

 to a little longer than the body of the scale. Infrequent in moist soil, throughout 

 most of Tex. to Ariz.; Neb. and Wyo., s. to Tex., N.M. and Ariz. 



Var. Drummondii (Nees) Friedl. "Perianth" scale equaling or surpassing the 

 achene and often cupped around it distally and adaxially, with 3 to 5 vascular 

 strands; mucro of floral scales less than two thirds as long as the body of the 

 scale. In Okla. (Comanche Co.), e. and n.-cen. Tex., N. M. (Bernalillo Co.) 

 and Ariz. (Pima Co.); from Mo. and Neb. s. and s.w. to Tex., N.M. and Ariz.; 

 intergrading with the last variety. 



Var. minor (Schrad.) Friedl. Mucro shorter than body of glume; "perianth" 

 scale shorter than the achene and usually more or less bifid. Ariz. (Cochise an'd 

 Pima COS.). 



9. Cyperus L. Flatsedge 



Herbs, usually with culms leafy near the base, often subscapose; inflorescence 

 terminal, an umbel-like aggregation of primary peduncles (each subtended by a 

 bract, usually) bearing spikes or heads of spikelets or the longer of the peduncles 

 each bearing smaller umbel-like aggregations of secondary peduncles (with or with- 

 out bractlets) each bearing spikes or head of spikelets or the whole inflorescence 

 contracted into a dense flowering mass with the true form obliterated; spikelets 

 usually borne in several rows on the spike or head axis, with a minute bract basally 

 and either with several to many fertile scales distichously arranged or else reduced 



415 



