108 CYPERACEAE 



2. E. Chamissonis C. A. Mey. Stems 1-7 dm. high, somewhat triangular; 

 upper sheaths inflated, bladeless; leaf-blades filiform, triangular-channelled, 

 3-10 cm. long; bristles often reddish-brown. E. russcolatum Fries. Bogs: 

 N.B. — Ont. — Wye— Ore. — B.C.; Evu-asia. Mont. — Subalp. Je-Au. 



3. E. callitrix Cham. Stems obtusely 3-angled, 2-5 dm. high; leaf-blades 

 filiform, triangular-channeled; glumes thin, ovate-lanceolate or the lowest 

 lanceolate, acimiinate, pale brown. E. vaginalwnTorr., noth. Bogs: Newf. — 

 Mass. — Pa. — Sask. — B.C. — Alaska. Boreal — Mont. Je-Au. 



4. E. opacum (Bjornstr.) Fernald. Stem terete or nearly so, 3-6 dm. high; 

 basal leaves elongate, filiform, channeled; stem-leaves reduced to 2 or 3 close 

 sheaths; glumes thin, ovate-lanceolate or the inner ones linear-lanceolate, acum- 

 inate. Bogs: Me. — Mass. — B.C. — Yukon; Eurasia. Boreal — Mont. My-Jl. 



5. E. gracile Koch. Stem slender, smooth, terete, 3-6 dm. high; blades of 

 the stem-leaves 2-3 cm. long, the basal ones longer; bracts about 1 cm. long; 

 spikelets 2-6, on pubescent peduncles; glumes ovate, gray or nearly black, 

 acutish, with prominent midrib. Bogs: Que. — N.Y. — Colo. — Calif. — B.C.; 

 Eurasia. Plain — Mont. Je-Aa. 



6. E. angustifolium Roth. Stem smooth, obtusely triangular above, 3-6 

 dm. high; blades rough-margined, 3-8 mm. wide; bracts 2-i, often black at the 

 base; spikelets 2-12, ovoid or oblong; pedmicles smooth; glumes ovate-lanceolate, 

 acute or acuminate, purple-green or brown. E. poly.stachyon L., in part. E. 

 ocreatum A. Nels. Bogs: Newf. — Me. — 111. — N.M. — Ore. — Alaska; Eurasia. 

 Suhmont. — Subalp. Je-Au. 



7. E. viridicarinatum (Engelm.) Fernald. Stem 3-6 dm. high; leaf-blades 

 2-6 mm. wide, the upper 15 cm. long or less; bracts not black at the base; spike- 

 lets 5-30; peduncles fine-hairy; glumes ovate-lanceolate; achenes oblong-obovoid. 

 E. poli^fitnckyon Am. auth., mainly. Bogs and wet meadows: Newf. — Ga. — 

 Ohio— Wyo.— B.C. Suhmont. Jl-Au. 



8. LEUCOCOMA Ehrh. Alpine Cotton-grass. ' 



Perennial bog plants, with rootstocks. Stems triangular. Spikelets soh- 

 tary, usually subtended by a subulate bract and attached slightly obliquely. 

 Glumes spirally arranged, all usually subtending perfect flowers. Perianth of 

 6 white soft bristles, at maturity exserted far beyond the glumes. Stamens 3. 

 Styles deciduous. Achenes obovoid, somewhat 3-angIed, without tubercle. 

 [Trichophoruni Pers., in part.] 



1. L. alpina (L.) Rydb. Stems numerous, not tufted, 1.5-2.5 dm. high; 

 leaves subulate, 6-20 mm. long, triangular, channelled; lower sheaths often 

 bladeless; glumes oblong-lanceolate, yellowish brown with slender midvein. 

 Eriophorum alpinuni L. Cold bogs: Newf. — Conn. — Mich. — B.C.; Eurasia. 

 Mont. — Alp. Je-Au. 



9. SCIRPUS L. Bulrush, Club-rush, Tule. 



Annual or perennial, caulescent or scapose herbs. Leaves grass-like, or in 

 many species reduced to basal sheaths. Spikelets terete or somewhat flattened, 

 solitary, capitate or umbellate. Glumes spirally arranged, some of the lov/er 

 often empty. Flowers perfect. Perianth of 1-6 barbed, pubescent or smooth 

 bristles, rarely wanting. Stamens 2-3. Style wholly deciduous, not swollen 

 at the base, or rarely its base pei'sistent as a small tip. Stigmas 2-3. Achenes 

 triangular or lenticul-.r, rarely plano-convex. 



Involucre of a single bract or wanting. 



Spikelets solitary, rarely two together; plants tufted (except No. .5). 



Annuals; stamens 2; bristles none. 1. S. coloradensis. 



Perennials, with rootstocks. 



Involucre none. 2. S. pauciflorus. 



Involucre present, consisting of one erect bract. 



Bract scarcely exceeding the spikelet, often shorter; bog plants. 



Bristles 6, longer than the achenes. 3. S. caespitosus. 



Bristles none. 4. S. pumilus. 



Bract at least twice as long as the spikelet; aquatic plants. 



5. S. sublerminalis. 



