SEDGE FAMILY 109 



Spikelets normally more than one, usually several, sometimes numerous. 



Spikelets few, 1-12, appearing lateral, in a single capitate cluster. . , , , 



Annuals, with fibrous roots, tufted; achenes dark, transversely wrmkled. 

 Spikelets obtuse; achenes plano-convex. - 6. 5. Ilailn. 



Spikelets acute; achenes 3-angular. 7. 5, saximontanus. 



Perennials, with rootstocks; aclieues plano-convex, obovate. 



Stem sharply 3-angled. ^ o o ■ 



Spikelets acute: bracts long: glumes awned. 8. S. amencanus. 



Spikelets obtuse; bracts short; glumes mucronate. 9. 5. Olncyi, ^ 

 Stem terete, striate. 10. S.nevadensis. 



Spikelets numerous in small clusters of 1-7, arranged m compoimd umbels; per- 

 ennials with stout rootstocks. 

 Style 2-cleft; achenes obovate and plano-convex, brown. 



Achenes 2 mm. long, nearly as long as the glumes; spikelet^ ovpid. 



11. S. ralidus. 



Achenes 3 mm. long, distinctly shorter than the glumes; spikelet oblong- 

 cvlindric 12. S. occtderUaUs. 



Stvle 3-cleft: achenes obcordate, 3-angled, yellowish. 13. S. heterochaetus. 



Involucre of\wo or more leaves with flat blades; perennials, with rootstocks. 



Spikelets 3-10. capitate, relatively large. , „ . i ^ ^^'i ^f: P^'^^^f/^f- 



Spikelets numerous, in compound umbels or in umbellate heads, relatuelj smaU. 

 Bristles downwardlv barbed, not much exceeding the friut. 



Style-branches 2; achenes plano-convex; bristles mostly 4. ^ 



style-branches 3; achenes oblong, 3-angular; bristles ^- ,^ „ , . 

 Plant dark green; glumes acut«; achenes pale brown. 10. b. atronrens. 

 Plant pale; glumes rough-awned; achenes straw-colored. 



17. o. pc 1 1 1(1 us m 



Bristles 6, smooth, much exceeding the glumes at maturity; achenes 3-angled, 



1 * * 1 



Spikelets all sessile; glumes brown. . i_ , , 18. S. cyperimis. 



Snikelets mostly pedlceled; glumes mostly greenish black. ^ , . , 



19. lS. alrocinctus. 



1. S. coloradensis Britt. Annual; stems filiform, 2-5 cm. high; spikelet 

 bractless, hnear-oblong, acutish, 3-5 mm. long, 2 mm. thick; glumes lanceolate, 

 acutish; keel green, bordered with two brown bands and scarious margms; 

 achenes brown, obovate, 1 mm. long, 3-gonous, finch' papillose. Shores: Colo.; 

 Nev. Plain. 



2. S. pauciflorus Lightf. Rootstock filiform; stems 3-angled, filiform, leaf- 

 less, 7-25 cm. high; spikelet oblong, compiessed, 4-10-flowered, 4-6 mm long; 

 glumes brown with lighter margins and midrib, lanceolate, acummate; bristles 

 2-6, usually longer than the achenes; achenes obovoid, abruptly beaked, finely 

 reticulate. Wet soil: Que.— INIe.—X.Y.—N.M.— Calif.— B.C.; Eurasia. Mont. 



—Subalp. Jl-0. 



3. S. caespitosus L. Stems light green, filiform, 1-4 dm. h 



numerous, the upper one bearing a short blade; spikelet ovoi , v- v 



long- glumes yellowish brown, ovate, obtuse; achenes oblong, 3-angled, brovvn, 

 acute. Bogs and wet places: Greenl.— 111.— Colo.— Wash.— Alaska; Eurasia. 



Mont. — Alp. Je-Au. 



4. S. pumilus Vahl. Stems terete, 1 dm. high or less, sheathed at the base; 

 upper sheath with a short blade; spikelet roundled-o void ; glumes ovate, acute 

 or pointed, brown with green midrib and margins; achene 3-angular smooth. 

 S. alpinus Schleicher. Alpine wet places: Canadian Rockies; Alps. Jl-Au. 



5. S. subterminalis Torr. Stem slender, terete, nodulose, 3-10 dm high; 

 leaves very slender, 1.5-6 dm. long, 0.5-1.5 mm. wide; spikelet oblong-cylindric, 

 6-15 mm. long; bract subulate, erect, 1-2.5 cm. long; glumes ovate-lanceolate, 

 acute, light brown with green midrib; bristles 6, rarely equallmg the achenes; 

 these obovoid, 3-angled, dark brown, smooth. Ponds and streams: ^eu-f.- 

 S.C.— Mich.— Ida.— Wash.— B.C. Snbmont. Jl-Au. 



6. S. Hallii A. Grav. Stems slender, smooth, obtusely 3-angular, 1-3 dm. 

 high; upper sheath bearing a filiform blade 1-6 cm. long; spikelets 1-7, capitate, 

 obloAg-cylindric, obtuse, 6-12 mm. long; bract 2-10 cm long; glumes ovate- 

 lanceolate, greenish brovs-n, acuminate; bristles none ^^ et places: Mas:,.- 

 Fla.— Tex.— Colo.— Utah— Mex. Plain— Sub mord. Jl-S. 



7. S. saximontanus Femald. Stems slender, smooth, 1-3 dm. high, tufted, 

 short-leaved at the base; bract erect, one-half to one-fourth as long as the stem; 



