with white cartilaginous thickening and on the fertile side with 2 hyaline wings 

 (eventually becoming papery) clasping the achene and at the base of each inter- 

 node (above each node) abscising so that the whole spikelet breaks up into joints 

 each comprising a scale, the next lower internode and the attached wings and 

 achene; scales small, brownish, with a number of nerves, each persistent on its 

 joint; stamens 3; achenes brownish, unequally trigonous, the 2 smaller (sharper) 

 angles adaxial, clasped by the wings. C ferax Rich., C. speciosus Vahl, C. fer- 

 ruginescens Buckl. 



In mud of swamps, ditches and streams, at edge of lakes and creeks, abundant 

 in all parts of Tex. and Okla., N.M. (San Juan Co.) and Ariz, (widespread); 

 perhaps our most abundant flatsedge and one of the most variable, but it is im- 

 possible to distinguish segregate taxa, spring-fall, occasionally, winter; semi- 

 cosmopolitan in temp, and trop. regions. Passing through the form called C. 

 Eggersii Boeck. to C. macrocephalus Liebm. with a headlike inflorescence. 



10. Cyperus articulatus L. Chintul. Fig. 220. 



Perennial forming colonies with creeping scaly rhizomes 1.5-6 mm. thick; culms 

 rising at intervals 7-50 mm. apart on the rhizomes, erect, 5-14 dm. long, 2-8 

 mm. thick, nearly terete or only vaguely triangular, septate at intervals of 5-50 

 mm.; leaves only few, toward the base, reduced to small essentially bladeless 

 sheaths; bracts few, 3-11 mm. long; inflorescence comprising 4 to 12 glomerules 

 of spikelets, some glomerules nearly sessile and some on slender nodding peduncles 

 to 12 cm. long; glomerules with up to 20 spikelets, essentially bractless; spike- 

 lets 6-25 mm. long, about 2 mm. broad, laterally compressed, the axis remaining 

 intact after the scales and achenes fall; scales keeled, the lower sides decurrent on 

 the spikelet axis as readily deciduous wings 0.2-0.4 mm. wide and about 1 mm. 

 long; stamens 3; connective very minutely prolonged beyond the end of the 

 anther; achene unequally trigonous. 



Abundant in moist or wet clay meadows, in mud on edge of lakes, along streams 

 and above inlets, s.e. Tex. and Rio Grande Plains, rare n. to s. part of n.-cen. Tex. 

 (Comal, Travis and McLennan cos.), May-Oct.; Braz. and Col. n. to Gulf States. 



11. Cyperus Iria L. Fig. 221. 



Tufted annual; culms 8-60 om. long, erect; leaves crowded near the base, 

 shorter than the culm; inflorescence 4-12 cm. long (not including the bracts), an 

 umbel-like aggregation of 5 to 8 extremely unequal peduncles each bearing an 

 irregular panicle of several spikes each with a number of ascending spikelets the 

 total inflorescence with 100 to 600 spikelets; bracts about 4, much longer than 

 the inflorescence; spikelets 3-10 mm. long, 1.3-1.8 mm. broad, with 2 to 22 

 flowers, the axis persisting and remaining intact even after the achenes and scales 

 fall; scales nearly orbicular or as seen laterally and folded appearing obovate, 

 about 1.5 mm. long, rounded to emarginate, mucronulate, with about 4 nerves in 

 the incurved weakly keel-like median, brownish or golden-brown, the hyaline 

 margins tending to fold in and meet on the adaxial side of the achene, decurrent 

 below as thin striations but not as wings; stamens 2 or 3; achene trigonous, 1.2- 

 1.3 mm. long. 



Wet clay in coastal rice-growing areas, in water of freshwater canals and on 

 edge of ponds, in Okla. (McCurtain. LeFlore and Pittsburgh cos.) and s.e. Tex. 

 (Colorado, Harris, Jackson and Matagorda cos.), locally common, July-Sept.; s.e. 

 Asia (n. to Korea and Mongolia), N. Austral., Malaysia, India, Afr. Madag., 

 Iran, Afghan., adv. in scattered parts of Am., especially in the Gulf and s. Atl. 

 States; W.I. 



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