SCIRPUS CYPERACE^E 691 



ERIOPHOKUM 



in capitate clusters at the ends of the usually spreading raylets : scales 

 brown with a green midrib, obtuse or subacute : bristles 4, somewhat lon- 

 ger than the achene: stamens 2: style 2-cleft : achenes oblong-obovate, 

 nearly white, plano-convex or with a low ridge on the back, pointed. In 

 swamps and wet woods, Alaska to California and the Atlantic States 



S. atroyirens Muhl. Gram. 43. Stems rather slender, leafy, 2-4 feet 

 high, from slender perennial rpotstocks : leaves elongated, rough on the 

 margins, dark green, 3-6 lines wide one or two of them usually exceeding 

 the inflorescence : umbel simple or 1-2-compound : spikelets ovoid-oblong, 

 acute, 6-20 in the dense capitate clusters at the ends of the rays or raylets : 

 scales greenish -brown,oblong, acute, the midrib excurrent, bristles usually 

 6, about as long as the achene: stamens 3: style 3-cleft: achene obovoid - 

 oblong, 3-angled, pale dull brown. In swamps, Oregon to Nova Scotia 

 and Georgia. 



S. lineatus Michx. Fl. i, 32. Perennial by stout rootstocks: stems 

 rather slender, erect, 1-3 feet high, leafy : leaves light green, shorter than 

 the stem, 2-4 lines wide, the upper ones and those of the involucre not 

 exceeding the inflorescence, flat, rough on the margins : umbels terminal 

 and commonly also axillary, decompound, the rays very slender, becoming 

 pendulous : spikelets mostly solitary at the ends of slender raylets, oblong, 

 obtuse, 3-5 lines long: scales ovate or oblong, reddish-brown with green 

 midrib: bristles 6, weak, smooth, much longer than the achene : stamens 

 3: style 3-cleft: achenes oblong, pale brown, narrowed at both ends, 

 3-angled, short-beaked. In wet places, Oregon to Texas, Georgia and 

 Ontario. 



3 Stems leafy, bearing a sessile head of spikelets subtended 

 by a few involucral bracts. Bristles elongated, the barbs directed 

 upward. 



S. eriniger Gray Proc. Am. Acad. vii, 392. Stems slender, 3 inches 

 to 3 feet high, from* slender matted rootstocks, triangular and striate, 

 rough above : leaves flat, rough on the margins, the radical one elongated 

 but shorter than the stem, the cauline only an inch or two long, distant, 

 the uppermost usually very near the top: involucral bracts broad and 

 scale-like, acuminate, 2-4 lines long : spikelets 5-9, oblong, 3-4 lines long : 

 scales thin and soft, brownish, oblong: bristles 6: filaments slender, much 

 exserted: style 3-cleft: achenes oblong, 3-angled, acute and shortly beaked, 

 a line long. In marshes, southern Oregon to California. 



4 ERIOPHORUM L. Sp. 52. 



Low herbs with creeping perennial rootstocks, triangular or 

 nearly terete stems, grass-like leaves and small perfect flowers in 

 terminal solitary or umbellately clustered spikelets subtended by 

 a one- to several-leaved involucre or naked. Scales spirally im- 

 bricated, usually all fertile. Perianth of few to many filiform 

 smooth soft exserted bristles. Stamens 1-3. Style 3-cleft. 

 Achenes 3-angled, oblong, ellipsoid or obovoid. 



* Involucral leaves none : spikelets solitary. 



E. vaginatum L. Sp. 52. Stems stiff, tufted, obtusely triangular, 

 smooth, slender, 8-16 inches high, leafless except at base, bearing 2 inflat- 

 ed sheaths, the upper one usually above the middle : leaves stiff, filiform, 

 triangular, channelled, shorter than or sometimes exceeding the stem : 

 s pikelet ovoid, erect : scales ovate-lanceolate or the lowest lanceolate, acu- 

 minate, purple-brown, thin: bristles numerous, white, straight, glossy, 

 4-5 times as long as the scale: anthers linear: achene obovoid, obtuse 



