CYPERACEAE. l8l 



lets terminal, solitary, capitate or umbelled, subtended by a i-several-leaved 

 involucre, or naked. Scales spirally imbricated, usually all fertile. Flowers 

 perfect. Perianth of 6 or numerous filiform smooth soft bristles, which are white 

 or brown, straight or crisped, and exserted much beyond the scales at maturity. 

 Stamens 1-3. Style 3-cleft. Achene 3-angled, oblong, ellipsoid or obovoid. 

 [Greek, signifying wool-bearing, referring to the soft bristles.] About 10 species, 

 in the northern hemisphere. Besides the following, one occurs in Alaska. 



Spikelet solitary ; involucral leaf short or none. 



Bristles only 6, white, crisped, very long. 1. E. alpinum. 



Bristles numerous, straight or slightly crisped. 

 Bristles bright white. 



Culm with 2 inflated bladeless sheaths; achene obovoid, obtuse. 



2. E. vaginatum. 

 Only the upper sheath bladeless, or all blade-bearing; achene linear-oblong, 

 acute. 3. E. Scheuchzeri. 



Bristles reddish-brown 4. E. russeolum. 



Spikelets several, umbellate or capitate ; involucre 1-4-leaved. 



Achene obovoid, obtuse ; spikelets umbellate. 5. E. polystachyon. 



Achene linear-oblong, acute ; spikelets capitate or some of them peduncled. 



Leaves channeled or 3-sided ; bristles 4-6 times as long as the scale, bright 

 white. 



Upper part of culm and the peduncles rough ; bristles 2-2.5 cm - long. 



6. E. paucinervium. 

 Plant smooth or nearly so throughout ; bristles 1-1.5 cm. long. 



7. E. gracile. 

 Leaves flat ; bristles 3 times as long as the scale, brown (rarely white). 



8. E. Virginicutn. 



1. Eriophorum alpinum L. Alpine Cotton-grass. (I. F. f. 637.) Peren- 

 nial by short rootstocks, sending up numerous filiform triangular roughish culms, 

 1.5-2.5 dm. high. Leaves subulate, 6-20 mm. long, triangular, channeled, borne 

 near the base of the culm, the lower sheaths often bladeless; spikelet terminal, 

 small, erect; involucral bract subulate, mostly shorter than the spikelet, sometimes 

 wanting; scales oblong-lanceolate, yellowish brown, firm, the midvein slender; 

 bristles 6, white, crisped, 4-7 times as long as the scale; achene narrowly obovoid- 

 oblong, brown, apiculate, dull. In bogs and on high mountains, Newf. to Hudson 

 Bay and the N. W. Terr., south to Vt., N. N. Y. and Minn. Also in Europe and 

 Asia. Summer. 



2. Eriophorum vaginatum L. Sheathed Cotton-grass. (I. F. f. 638.) 

 Culms stiff, obtusely triangular, smooth, slender, 2-4 dm. tall, bearing two distant 

 inflated sheaths, the upper one usually above the middle. Leaves stiff, filiform, 

 triangular, channeled, shorter than or sometimes overtopping the culm; involucral 

 leaf wanting; spikelet solitary; scales ovate-lanceolate or the lowest lanceolate, 

 acuminate, purple-brown, thin; bristles numerous, white, straight, glossy, 4-5 

 times as long as the scale; anthers linear; achene obovoid, obtuse, brown, dull, 

 minutely apiculate. In bogs, Newf. to Alaska, Mass., Penn. and Minn. Also in 

 N. Europe and Asia. June- Aug. 



3. Eriophorum Scheuchzeri Hoppe. Scheuchzer's Cotton-grass. 

 (I. F. f. 639.) Similar to the preceding, but the sheaths all blade-bearing or only 

 the upper one bladeless; culms slender, smooth, nearly terete. Leaves usually 

 much shorter than the culm; scales ovate-lanceolate, long-acuminate, purple- 

 brown; bristles white or slightly yellowish, weak, nearly straight; "anthers cor- 

 date-ovate;" achene narrowly oblong, acute, brown, dull, subulate-beaked. In bogs, 

 Newf. and Lab. to Manitoba, Alaska and Ore. Also in Europe. Summer. 



4. Eriophorum russeolum Fries. Russet Cotton-grass. (I. F. f. 640.) 

 Culms triangular, erect, smooth, longer than the leaves. Upper sheath inflated, 

 bladeless. mucronate, or rarely with a short subulate blade usually borne below the 

 middle of the culm; leaves filiform, triangular-channeled, mucronate, 2-10 cm long; 

 spikelet erect; involucre none; scales ovate-lanceolate, acuminate, thin, purplish 

 brown with nearly white margins; bristles numerous, bright reddish brown, 3-5 

 times as long as the scale; achene oblong, narrowed at each end, apiculate. 

 Scarcely differs from the preceding species except in the color of the bristles and 

 Che bhorter-pointed achene. In bogs, Newf. to Quebec. June-Aug. 



