196 CYPERACEAE (SEDGE FAMILY) 



3-cleft. Achene acutely triangular. (Name composed of ^pLov, wool or cotton^ 

 and <pop6sy bearing.) 



§ 1. Spikelet solitary ; involucre none ; the lowest scale of the splke- 

 let enlarged and thickened ; stem-leaves reduced to mostly 

 bladclesB sheaths a. 



a. Stoloniferous, culms solitary ; empty scales at base of spikelet 



few (7 or less) ; flowering spikelet cylindrlc, in fruit becom- 

 inf? obovoid. 



Bristles reddish or cinnamon-color 1. K GhamiBeonia. 



Bristles white U) ^. Oharndssotvis, v. albidtMn. 



U-. Nonstoloniferous, culms tufted; empty scales 10-15; flowering 

 spikelet obovoid or globose, in fruit becoming depressed- 

 globose. 

 Densely tufted, the culms very many; upper sheaths dis- 

 tinctly inflated ; culm tripronous and scabrous at tip . 2, M. callitrix. 

 Loosely tufted, culms very few; upper sheath close ; culm 



terete, glabrous at tip 3. -£". opacwm. 



§2. Spikelets 2-several ; involucre of l-several leafy bracts h. 



6. Leaves very slender, 1-1.6 mm. broad, triangular-channeled 

 throughout; involucre a single erect short bract. 

 Upper cauhne leaf with the sheath longer than the blade . 4. E. gradle. 

 Upper cauline leaf with the sheath shorter than the blade . 5. E. tenellum, 



b. Leaves broader, flat at least below the middle; involucral 



bracts 3 or more c. 

 V. Scales of spikelet with only 1 prominent rib ; stamens 8. 



Midrib of scale prominent only below the membranous tip ; 

 upper leaf-sheaths dark -girdled at summit. 



Leaves 1.5-4 mm. broad . 6. E. anguatifoliwm. 



Leaves 5-8 mm. broad {^) E.angustifoliumyV,ma^us. 



Midrib prominent to the tip of the scale ; leaf-sheaths not 

 dark -gird led. 



Spikelets mostly peduncled 1. E. viridi-carinatum. 



Spikelets sessile in a glomerule . . . (7) E viri'di-carmatum^v. EeUoicsii. 

 o. Scales of the spikelet with several prominent ribs ; stamen 1. 



Bristles copper-color or brown .... . 8. E. virginicum. 



Bristles white except at base . . . . . (8) ^. tdrginicum, v. album. 



1. E. Chamissbnis C. A. Mey. Culms soft, subterete, 1-8 dm. high ; hasal 

 leaves slender., channeled, the upper scarcely inflated sheaths mostly bladeless ; 

 flowering spikelet 1.5-2 cm. long; its scales brownish lead-color with broad 

 whitish margins, hluntish; bristles reddish. (E. russeolum Fries.) — Locally 

 in bogs, Lab. to N. S. and N. B. ; Ont. ; Rocky Mts., etc. Fr. July, Aug. 

 (Eurasia.) Var. Albidum (F. Nylander) Fernald. Bristles white. — Que. and 

 N. B. ; Alaska, etc.. (Eurasia.) 



2. E. cillitrix Cham. (Hare's Tail.) Culms stiff and wiry, densely tvfted^ 

 1.5-7 dm. high; basal leaves filiform-trigonous, scabrous; upper bJadeless 

 sheaths inflated ; flowering spikelet obovoid or globose, 0.8-1.5 cm. long ; scales 

 lead-color with pale margins, ovate to ovate-lanceolate, long-acuminate; fruit- 

 ing spikelet 2.5-6 cm. broad ; bnstles bright white. {E. vaginatum Am. 

 authors, not L.). — Bogs and mountain slopes, Lab. to Alaska, s. to Pa., 

 Mich., Wis., and Man. Fr. May-July. (Asia.) 



3. E. opacum (Bjomstr.) Fernald. Similar; culms terete, glabrous, fili- 

 form, forming loose small titfts ; leaves glabrotis ; upper sheaths close ; flowering 

 spikelet rarely 1 cm. long; scales lead-color, lance-attenuate; fruiting spikelet 

 2-3.5 cm. broad ; bristles sordid lohite. — Locally on bogs, South Ashburnham, 

 Mass. (Forbes); Ont. to Sask. and the Rocky Mts. Fr. June, July. (Eurasia.) 



4. E. grAcile Roth. Weak and slender, glabrous, the subtei'ete culm 2-6 

 dm. high, with no young basal leaves developed at flowering season; upper 

 cauline leaf-blade smooth, round-tipped, 1-4 cm. long; involucre dark at base; 

 spikelets 2-5, mostly on short slender pubescent peduncles (O.ri-o cm. long), 

 in anthesis 7-10 mm. long, in fruit 1.6-2 cm. long ; scales lead-color or blackish; 

 achenes 1.5-2 mm. long; bristles white. — Cold bogs and swamps, Gulf of St. 

 Lawrence to B.C., s. to Ct., Pa,, Mich., Neb., and Cal. Fr. May-July. 

 (Eurasia.) 



5. E. ten§llum Nutt. Culms stiff, obtusely trigonous, scabrous above, 3-9 

 dm. high, with long slender green pointed basal leaves ; upper cauline leaf-blade 

 scabrous, pointed, 3-18 cm. long; involucre brown or straxo-color at base; 

 spikelets 3-6, on scabrous peduncles, in fruit 2-2.8 cm. long; scales greenish 



