gonous; leaves few, basal, consisting only of mostly open brownish sheaths whose 

 margins are rather regularly retrorsely fimbriate-filiferous: primary bract appear- 

 ing as a continuation of the culm, 18-70 mm. long (other bracts reduced, scale- 

 like), shorter than the inflorescence; inflorescence 4-12 cm. long, decompound 

 with a number of usually drooping branches, altogether with 50 to 150 spikelets; 

 spikelets lance-ovoid, 6-1 1 mm. long, of 30 to 50 flowers; scales about 3 mm. 

 long, ovate to obovate, dark-brown, some of them emarginate, mucronate, the 

 distal margins essentially entire; bristles 2 to 4, subligulate, reddish-brown, each 

 one on each side with 15 to 20 reddish-brown closely spaced spreading or often 

 somewhat retrorse projections (not barbellate); styles mostly bifid; achene obovate, 

 apiculate, about 2 mm. long, brown, plano-convex or biconvex. 



Scattered in mud and shallow water of ponds and lakes throughout Tex. except 

 the Plains Country, Okla. (Creek, Sequoyah and Stephens cos.), N. M. (McKinley 

 and Rio Arriba cos.) and Ariz. (Mohave, Maricopa, Pima, Santa Cruz and Yuma 

 COS.), spring-summer; warmer parts of Am., n. to Gulf States, s. Ariz, and s. 

 Calif. 



16. Scirpus heterochaetus Chase. 



Similar to S. acutiis; culms slender, rarely 1 cm. thick, pale green, firm; panicle 

 with ascending to spreading very slender smooth to barely scabrous rays; bract- 

 lets whitish-brown, glabrous; spikelets mostly solitary, pale-brown to drab or 

 whitish-green, lance-acuminate to slenderly ellipsoid, acute to subacuminate, 

 7.5-23 mm. long; scales firm or subcoriaceous, deeply emarginate, often slightly 

 red-dotted, glabrous; bristles 2 to 4 (mostly 2), fragile, unequal, shorter than 

 achene, barbellate or smooth; filaments broad; style 3-cleft; achene trigonous but 

 twice as broad as thick. 



Calcareous or other basic deadwaters, shores and swamps, in Okla. (Waterfall), 

 June-Sept; e. Mass., s.w. Que., w. Vt. and n. N.Y., Wise, to N.D., s. to cen. Ky., 

 111., Mo. and Okla.; n.w. Ida., Wash, and Ore. 



17. Scirpus etuberculatus (Steud.) O. Ktze. Fig. 183. 



Culm 1-2 m. tall, 3-angled (usually sharply so above, obtusely so below), the 

 sheath at base extended into a long slender triangular and channeled leaf; in- 

 volucral leaf similar (1-2.5 dm. long), continuing the culm; spikelets cylindric 

 (1-2 cm. long), single or sometimes proliferously 2 or 3 together, nodding on the 

 apices of the 5 to 9 long filiform and flattened peduncles or rays of the dichotom- 

 ous umbel-like corymb, or the central one nearly sessile; scales loosely imbricated 

 oblong-ovate, acute, pale, thin and scarious, with a greenish nerved back; bristles 

 6, firm, furnished above with spreading hairs rather than barbs, equaling the 

 slender abrupt beak of the obovoid-triangular shining achene 2.5-3 mm. (-4) long. 



Ponds (in 1 to 3 ft. of water) and fresh to brackish marshes, very local, Fla. 

 to s.e. Tex. (Hardin Co.), n. to Del. and Mo. 



Often with a 2nd involucral bract, in this character and in its achene and 

 bristles showing alliance with S. fluviatilis. 



18. Scirpus acutus Muhl. Hard-stem bulrush, Tule, great bulrush. Fig. 184. 



Rhizomatous perennial forming extensive colonies; culms 1-3 m. long, rising 

 at close intervals from the rhizomes, 8-23 mm. thick near the base, long-tapered, 

 2-4 mm. thick just under the inflorescence, essentially terete to very obscurely 

 trigonous; leaves 1 or 2 per culm, confined to the very base, consisting of short 

 mostly open sheaths with nearly smooth to lacerate margins; blades obsolescent; 

 bract appearing as a continuation of the culm, (5-) 10-30 (-55) mm. long, shorter 

 than the inflorescence; inflorescence 3-10 cm. long, decompound, with several 

 drooping primary branches and 10 to 35 spikelets; spikelets lance-ovoid, at 

 maturity 8-15 mm. long, of 20 to 50 flowers; scales about 5 mm. long (the lower 



360 



