most of them on slender peduncles 4-10 mm. long, not in glomerules; spikelets 

 ovoid to ellipsoid, brown, 3-5 mm. long, of 40 to 100 flowers; scales elliptic, 

 1.5-2 mm. long, brown, acute; bristles several, very long, brown, far-surpassing 

 the scales; achenes about 1 mm. long, oblong-apiculate, whitish, flattened-triangular 

 (the abaxial angle blunt, the inner 2 sharp). 5. rubricosm Fern. 



Wet or boggy places, in water and muddy places, in Okla. (Waterfall) and e. 

 Tex., summer; the var. cyperinus is widespread in e. U.S. and Can.; the var. 

 rubricosus is found mostly in s.e. U.S. but occurs n. to Mich, and N.E. 



5. Scirpus microcarpus Presl. Fig. 178. 



Perennial with stout rhizomes; culms stout, erect, leafy, subterete, 7-17 dm. 

 tall; leaves flat, broad, 1-2 cm. wide, margins scabrous, the blades acuminate, 

 often overtopping the stem; involucral leaves 2 to 5, the longer ones usually ex- 

 tending beyond the heads; inflorescence a loose spreading compound umbel, the 

 primary rays to 10 cm. long; scales green to brown, acute, ovate, with a promi- 

 nent midrib, not awned; bristles 4, downwardly barbed, somewhat longer than the 

 achene; stamens 2; style 2-cleft; achene whitish, ovate, lenticular, with an obscure 

 dorsal crest, mucronate, 1 mm. long. 



Along boggy streams, about springs and in mud at edge of stream, in N. M. 

 (Catron, Colfax, Taos and Rio Arriba cos.) and Ariz. (Apache, Navajo, Coconino, 

 Yavapai, Gila, Cochise and Pima cos.); Alas, to N.M., Ariz, and Calif. 



6. Scirpus atrovirens Willd. Fig. 179. 



Rhizomatous perennial; rhizome 2-6 mm. thick; culms 5-8 mm. thick basally, 

 8-15 dm. long, erect, somewhat trigonous in the upper portion, leafy; bracts 

 several, well-developed, leaflike, ascending or spreading, as long as or exceeding 

 the inflorescence; inflorescence complicatedly decompound, of 100 to 250 (to 500) 

 spikelets in glomerules which in turn are disposed in dense compound panicles, 

 some of the primary branches that bear the panicles 5-14 cm. long; spikelets ovoid 

 to narrowly ovoid, dark-brown to fuscous, of 20 to 40 flowers; bristles almost as 

 long as the achene; scales 1.5-3 mm. long, ovate, acute, with a strong midrib; 

 achene oblong, about 1 mm. long, in transection flattened-trigonous (the abaxial 

 angle blunt, the others sharp). 



Most of the U.S. (except Pac. States), in and along streams and in wet 

 meadows, about lakes and in sloughs. 



We have 2 varieties: 



Var. atrovirens. Scales with a minute mucro only. Rare in moist loam, e. 

 Tex. (Angelina Co.), summer; otherwise in e. U.S. and e. Can., one station in 

 Ariz. 



Var. pallidas Britt. Scales with a strong mucro or very short awn. 5. pallidus 

 (Britt.) Fern. Rare in Tex. Plains Country (Panhandle), Okla. (Osage, Adair, 

 Caddo and Woodward cos.), N. M. (Catron, Union, Colfax, Otero and San 

 Miguel COS.) and Ariz. (Apache and Navajo cos.), summer; in cen. and w. U.S. 



7. Scirpus georgianus Harper. 



Tufted perennial from thick ascending ligneous caudexes but not distinctly 

 rhizomatous; culms 5-15 dm. long, erect (some very shortly decumbent basally), 

 3-6 mm. thick just above the caudex, obscurely trigonous above, leafy; bracts 

 several, leaflike but reduced in size, ascending, shorter than the inflorescence; in- 

 florescence a decompound often droopy panicle, some of the longer branches 3-7 

 cm. long, the 50 to 120 spikelets not in glomerules but most of them on pedicels 

 2-8 mm. long; spikelets ovoid to usually cylindric, of 70 to 150 (to 200) flowers 

 at maturity; scales ovate, about 2 mm. long, acute, brown with very strongly pro- 

 nounced green or bufly midnerve; bristles several, about twice as long as the 

 achenes or as long as the scales but mostly crumpled and entangled and never 



352 



