GENUS 6. 



SEDGE FAMILY. 



3 2 5 



Eriophorum tenellum Nutt. Rough Cotton- 

 grass. Fig. 797. 



Eriophorum tenellum Nutt. Gen. Add. 1818. 

 E.paucinervium A. A. Eaton, Bull. Torr. Club 25 : 341. 



1898. 



Culm slender, stiff, obtusely triangular, rough on the 

 angles above, i-2$ tall, the sheaths all blade-bearing. 

 Leaves narrowly linear, i" wide or less, triangular- 

 channeled, rough-margined, the upper longer than its 

 sheath; involucral leaf commonly only i, stiff, erect; 

 spikelets 3-8, capitate or subumbellate, the longer- 

 peduncled ones drooping ; scales ovate or oblong, ob- 

 tuse or subacute, pale yellow to brown, the midvein 

 rather strong, often with a weaker nerve on each side ; 

 bristles numerous, bright white, 8"-i2" long, 4-6 times 

 as long as the scale ; achene linear-oblong, acute, 

 pointed, li" long. 



In bogs, Newfoundland to Hudson Bay, New Jersey, Penn- 

 sylvania and Illinois. Formerly confused with the next 

 preceding species. June-Sept. 



8. Eriophorum angustifolium Roth. Tall Cotton-grass. Fig. 798. 



Eriophorum polystachyon L. Sp. PI. 52, in part. 1753. 

 E. angustifolium Roth, Tent, i : 24. 1788. 



Culm stiff, smooth, obtusely triangular above, 

 nearly terete below, i-2 tall or less, all the 

 sheaths blade-bearing. Leaves flat, at least below 

 the middle, roughish-margined, ii"-4" wide, 

 tapering to a triangular channeled rigid tip, the 

 upper shorter than -or rarely overtopping the 

 culm, those of the involucre 2-4, often black at 

 the base, the longer commonly equalling or ex- 

 ceeding the inflorescence; spikelets 2-12, ovoid, 

 or oblong, clustered in a terminal umbel ; rays 

 filiform, smooth; scales ovate-lanceolate, acute or 

 acuminate, purple-green or brown, the midvein 

 not extending to the tip ; bristles numerous, bright 

 white, about i' long, 4-5 times as long as the 

 scale ; achene obovoid, obtuse, light brown. 



In bogs, Newfoundland to Alaska, Maine, Illinois, 

 Colorado and Oregon. Also in Europe and Asia. 

 E. polystachyon L. is confined to the Old World. 

 June-Aug. 



9. Eriophorum viridicarinatum (Engelm.) 



Fernald. Thin-leaved Cotton-grass. 



Fig. 799. 



E. latifolium viridicarinatum Engelm. Am. Journ. Sci. 



46: 103. 1844. 

 Eriophorum polystachyon latifolium A. Gray, Man. 



529. 1848. Not E. latifolium Hoppe. 



Similar to the preceding species but with thinner 

 green, grass-like leaves, which are flat, except at 

 the tip, i"-3" wide, the upper one 6' long or less, 

 those of the involucre not black at the base; spike- 

 lets usually more numerous, sometimes as many as 

 30, the rays finely hairy, elongated or sometimes 

 very short ; scales ovate-lanceolate, the midvein ex- 

 tending to the tip, sometimes slightly excurrent ; 

 achene oblong-obovoid ; bristles white or yellowish- 

 white. 



In wet meadows and bogs, Newfoundland to British 

 Columbia, New York, Georgia, Ohio and Michigan. 



