ones emarginate), thin-membranous, pale-brown and with conspicuous elongate 

 reddish glutinous spots (seen under a lens), the distal margin lacerate, the mid- 

 nerve scabrous and projected as a mucro or short awn; bristles 4 to 6, about 

 equaling the achene, retrorsely barbed, on each side of the bristle 10 to 16 well- 

 spaced barbs; styles mostly 2-branched; achene obovate, apiculate, plano-convex 

 or very unequally biconvex, (1.8-) 2.1-2.4 (-2.9) mm. long. 5. lacustris L. subsp. 

 glauciis (Sm.) Hartm., S. Tabernaemontani Gmel., S. lacustris var. occidentalis 

 Wats. 



Alkaline or calcareous mud, marshes, usually in water, in Okla. (Le Flore, 

 Ottawa, Blaine, Cimarron, Comanche, Bryan and Texas cos.) in the Tex. Plains 

 Country and Trans-Pecos, rare e. to n.-cen. Tex., widespread in N.M. and Ariz., 

 spring-fall; Eur., much of temp. N. A. s. to Gulf States, Chih., Coah. and Calif. 



This is perhaps only a variety of S. lacustris. Some specimens from the Texas 

 lower Rio Grande Plains seem to be intermediate between S. acutus and S. validus. 



19. Scirpus validus Vahl. Great or soft-stem bulrush. Fig. 182. 



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 or 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 20 to 120 spikelets; spikelets ovoid, 5-10 mm. 

 long, of 20 to 50 flowers; scales obovate, 3-4 mm. long, firm-membranous, dark- 

 brown, nearly smooth (occasionally with a few reddish gummy spots near the 

 midnerve), the distal margin nearly smooth to slightly lacerate, the midnerve pro- 

 jected as a mucro or short awn; bristles 4 to 6, mostly slightly surpassing the 

 achene, retrorsely barbed (on each side of each bristle 10 to 16 well-spaced barbs); 

 styles mostly 2-branched; achenes obovate, apiculate, plano-convex or very un- 

 equally biconvex, (1.5-) 1.9-2.1 (-2.2) mm. long. S. lacustris var. condensatus 

 Peck. 



In mud and usually in shallow water, Okla. (Alfalfa, Grady, Johnston and 

 Stephens cos.), infrequent in scattered parts of e, s.e. and n.-cen. Tex. and Rio 

 Grande Plains, N. M. (San Miguel and Taos cos.) and Ariz. (Coconino, Yavapai, 

 Gila, Pinal, Cochise and Santa Cruz cos.), spring-fall; temp. N.A. s. to S.A. 



Perhaps only a variety of S. lacustris. 



3. Eriophonim L. Cotton-grass 



About 20 species in North Temperate and Arctic areas, with one in South 

 Africa. 



1. Eriophorum polystachion L. 



Colonial from widely creeping rhizomes; culms subterete, mostly 2-6 dm. tall; 

 leaves basal and cauline; blade well-developed, the lower ones usually somewhat 

 elongate, 2-6 mm. wide, flat or essentially so for most of its length, becoming 

 narrow and triangular or channeled toward the tip; uppermost culm leaf with well- 

 developed blade usually equaling or exceeding the sheath; involucral bracts several, 

 unequal. 2 or more of them noticeably foliaceous at least above the broadened 

 more chartaceous base, the longest one usually surpassing or equaling the in- 

 florescence; spikelets 2 to 8, most or all of them individually pedunculate, in a 

 compact to open umbelliform cyme, the peduncle more or less compressed, smooth 

 or sometimes minutely scabrous-hirtellous; scales tawny to brownish or blackish- 

 green, very thin distally, the slender midrib attenuated distally and not reaching 



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