Local in ditches, sink-lakes, ponds and wet prairies, e. (Austin Co.) and s. 

 (Aransas, Bexar, Cameron, Hidalgo, Nueces and San Patricio cos.) Tex., Plains 

 Country (Tom Green Co.) and Panhandle (Hale and Lynn cos.), spr.-fall; Kan., 

 Mo., Neb., O., Okla. (Comanche Co.), S.D., Tex., Wyo., S.L.P. and Tarn. 



S. Bergsonii Schuyler. Styles mostly 3 -parted and achenes 3-angled; scales 

 broadly ovate, mostly 2.1-2.9 mm. long and 2.2-3 mm. wide; spikelet achenes 

 with fewer than 15 firm undulating transverse ridges. 



Local in ditches and on pond margins in s. Tex., (Kenedy, Kleberg and Nueces 

 COS.), summer-fall; endemic. Said to hybridize with S. Wilkensii in Kenedy and 

 Nueces counties. 



13. Scirpus americanus Pers. var. longispicatus Britt. Sword-grass, three-square 



BULRUSH. Fig. 181. 



Rhizomatous perennial; rhizomes extensively creeping, reddish-brown, 2-3 mm. 

 thick; culms rising at short intervals, (1-) 3-15 dm. long, 2-6 mm. thick, ascend- 

 ing in the distal half sharply triquetrous and often somewhat nodding; leaves 2 to 



4, usually 2, with involute blades several cm. long; principal bract solitary, appear- 

 ing as a continuation of the stem, (15-) 30-50 (-155) mm. long; (lower scales 

 of the spikelets often much longer than the rest and with strong venation, bract- 

 like); inflorescence a solitary spikelet or a glomerule of 2 to 4 spikelets; spikelets 

 sessile, 7-17 mm. long, 4-5 mm. thick, narrowly ovoid or lance-ovoid, of 28 to 50 

 flowers; scales (except lowest) obovoid, brown, 4-5 mm. long, lower ones 

 emarginate, with a well-marked buffy midnerve (prolonged into a short awn) and 

 firm to membranous deep-brown sides; bristles about 4, about equaling the achene, 

 retrorsely barbellate; style 3-branched, less commonly 2-branched; achene 2.5-3 

 mm. long, 1.8-2.5 mm. broad, broadly obovate, apiculate, plano-convex, smooth, 

 dark-brown when mature. Some of our plants have been known incorrectly as 

 var. polyphyllus (Boeck.) Beetle. 



Essentially throughout our region in low often moist ground, in water and 

 about seepage areas, spring-summer; nearly throughout temp, parts of the world. 



14. Scirpus OIneyi E. & G. Fig. 180. 



Rhizomatous perennial; rhizomes extensive, 2-4 mm. thick; culms rising at 

 intervals, 6-20 dm. long, 4-8 mm. thick, sharply triquetrous most of the length 

 (the sides often concave); leaves crowded at the base, usually 2 or 3, the lowest 

 ones with loose membranous sheaths and reduced or obsolete, the upper one 

 (which still appears basal) with a slightly longer blade; principal bract solitary, 

 appearing as a continuation of the stem, 1-4 (-15) cm. long; (lower scales of the 

 spikelets not differentiated from the rest); inflorescence a dense glomerule of 5 to 

 15 spikelets: spikelets sessile, 5-8 (-12) mm. long, 3-5 mm. thick, mostly ovoid, 

 of 24 to 30 (to 40) flowers; scales 3-4 mm. long, the lower ones emarginate, 

 brown, the midrib paler, prolonged as a mucro; bristles about 4, about equaling 

 the achene, retrorsely barbellate; style usually 2-branched, less commonly 3- 

 branched; achene 1.8-2.6 mm. long, 1.5-1.8 mm. broad, obovate, apiculate, plano- 

 convex or unequally biconvex. Our plants have been known incorrectly as 



5. chilensis Nees. 



Rare and scattered, wet alkaline or marshy soil, s.e. and e. Tex., Trans-Pecos, 

 Plains Country and probably elsewhere, N.M. (Grant, Otero and Socorro cos.) 

 and Ariz. (Apache and Coconino, s. to Cochise, Santa Cruz and Pima cos.), 

 spring-summer; temp. N.A.; also Br. Hond., Venez. and Chile. 



15. Scirpus californicus (C.A. Mey.) Steud. Giant Bulrush, Tule. Fig. 182. 



Perennial from tight subrhizomatous knots; culms closely tufted, 1-2 mm. long, 

 8-22 mm. thick near the base, 2-4 mm. thick near the inflorescence, bluntly tri- 



357 



