122 CYPERACEAE 



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9. ARENARIAE Kunth. Rootstocks long-creeping, dark-colored, tough, the 

 culms arising singly or in small clumps at intervals, mostly stiff, dark-tinged at 

 base, aphyllopodic. Leaf-blades narrow. Spikes several to many, more or less 

 closely aggregated, some or all gynaecandrous or staminate, some usually pistil- 

 late or androgynous. Lower bract or bracts short-prolonged; the others bract- 

 like. Perigynia appressed-ascending, plano-convex, sharp or wing-margined, 

 at least above, conspicuously rough-beaked, the beak sharply bidentate. Achenes 

 lenticular. Stigmas 2. 



16. C. siccata Dewey. Culms 2-9 dm. high, rough above; leaf-blades 2-3 

 mm. wide, flat or channeled; head linear-oblong, 2-3.5 cm. long, 5-10 mm. wide, 

 the 6-12 sp:kes closely aggregated, except the lower 1-3; perigynia few to several, 

 ovate-lanceolate, 5-6 mm. long, 2 mm. wide, much flattened, several-nerved, 

 the beak as long as the body. Dry soil and hills: Me. N.J. -Ariz. Alta. 

 Boreal -Mont. Submont. My-Jl. 



10. MUHLENBERGIANAE Tuckerm. Densely cespitose or in a few species 

 the rootstocks elongate, tough and dark-colored. Culms not flattened. Opaque 

 part of sheaths neither transversely rugulose nor red-dotted. Spikes usually 

 ten or less, androgynous or pistillate but never gynaecandrous, rarely at all 

 compound. Bracts from little to strongly developed. Perigynia plano-convex, 

 green or chestnut-tinged or light brownish in age, from appressed to reflexed, 

 often strongly spongy at base, nerveless or sparingly nerved, narrowly sharp- 

 margined, conspicuously beaked, the beak sharply bidentate. Achenes lenticular. 

 Style-base more or less thickened. Stigmas 2. 



17. C. Hoodii Boott. Culms 3-6 dm. high, rough above; leaf-blades 1.5-3.5 

 mm. wide, flat; head globose or oblong-ovate, 1-2 cm. long, 8-15 mm. wide, 

 the spikes several, with 5-10 ascending perigynia; perigynia lance-ovate, 4-5 

 mm. long, 1.75-2 mm. wide, obsoletely nerved, margined above, the beak one- 

 third the length of the body. Mountain meadows and slopes: Alta. 'Colo. 

 Calif. B.C. Mont. Submont. Je-Au. 



18. C. vallicola Dewey. Culms 2.5-6 dm. high, rough above; leaf-blades 

 about 1 mm. wide, flat or channeled; head 15-20 mm. long, 7 mm. wide; peri- 

 gynia 1-10, oblong-elliptic, 3.5 mm. long, 2 mm. wide, not nerved, margined 

 above, the short beak minutely serrulate. C. brevisquama Mackenzie. Dry 

 slopes: Wyo. Ore. Submont. My-Je. 



19. C. occidentalis Bailey. Culms 2.5-7.5 dm. high, rough above; leaf- 

 blades flat, channeled, 1.5-2.5 mm. wide; head 1.5-3 cm. long, less than 1 cm. 

 wide; perigynia usually 7-15, lance-ovate, 2.5-3.5 mm. long, 1.75 mm. wide, 

 nerveless, margined above, the serrulate beak one-third the length of the body. 

 Dry places: Wyo. -N.M. -Ariz. -Utah. Submont. -Subalp. My-Au. 



20. C. Hookeriana Dewey. Culms 2.5-5 dm. high, rough above; leaf- 

 blades channeled, 1.5-2.5 mm. wide; head 1.5-2 cm. long, about 7 mm. wide; 

 psrigynia few, strictly appressed, lanceolate, 4 mm. long, 1.5 mm. wide, nerve- 

 lass, margined, the sarrulate beak half the length of the body. Dry soil: Alta. 

 Boreal Submont. Je. 



21. C. gravida Bailey. Culms 4-8 dm. high, sharply triangular, rough 

 above, cespitose from short rootstocks; leaf-blades flat, 3-14 mm. wide; head 

 2-3.5 cm. long, 8-14 mm. wide, ovoid or oblong; perigynia 10-20, dull, ascending, 

 broadly ovate or suborbicular, 3-4 mm. long, 2-3 mm. wide, little-nerved, the 

 baak one-third the length of the body. Prairies and plains: 111. Mo. -N.M. 

 Mont. Plain -Submont. My-Jl. 



11. MULTIFLORAE Kunth. Densely cespitose. Culms sharply triangular. 

 Opaque part of sheaths usually transversely rugulose, red-dotted. Spikes num- 

 erous, small, androgynous or pistillate, but never gynaecandrous, the lower 

 more or less compound. Bracts frequently conspicuous. Perigynia plano-convex, 

 not very thick, yellowish or yellowish brown, appressed-ascending or somewhat 

 spreading, not thick-walled, somewhat spongy at base, short-stipitate, sharp- 

 margined, more or less nerved, conspicuously rough-beaked, the beak bidentate. 

 Achenes lenticular. Stigmas 2. Style-base more or less enlarged. 



