368 CYPERACE.E. (SEDGE FAMILY.) 



Var. digynus, Boeck. Style 2-cleft, akene not at all angled on the back, 

 stamens 2, and bristles 4. S. microcarpus, Presl, of Gray's Manual. From 

 California to Colorado and across the continent northward. The type is 

 rarely collected in New England. 



8. S. atrovirens, Muhl. Very similar to the last: panicle more con- 

 tracted, the smaller spikelets crowded in denser and larger clusters: scales 

 narrower and narrow/,!/ acuminate : bristles scarcely barbed below the middle : 

 style 3-cleft : akene oblong-obovate, more acuminate, slightly angled on the back. 

 In wet meadows and bogs from Colorado to California and Oregon, and 

 eastward to New England. 



# * Bristles capillary, naked, not barbed, elongating, becoming tortuous and 

 entangled, much longer than the triangular akene. 



9. S. lineatUS, Michx. Stem triangular, leafy, 1 to 3 feet high : leaves 

 linear, flat : umbels terminal and sometimes axillary, loose, drooping, the 

 terminal with a 1 to 3-leaved involucre much shorter than the long slender 

 rays : spikes oblong, becoming cylindrical, on filiform drooping pedicels : 

 bristles at maturity scarcely exceeding the green-keeled and pointed scales : 

 akene sharp- pointed. From New England to Wisconsin and southward, 

 coming into our range from W. Kansas. 



3. ERIOPHORUM, L. COTTON-GRASS. 



Distinguished from Scirpus chiefly by very numerous naked silky bristles 

 which become loug-exserted in fruit. Style very slender and elongated, 

 3-cleft. Akene acutely triangular. Perennials with creeping rootstocks. 



1. E. gracile, Koch. Stem very slender, 1 or 2 feet high: leaves slender, 

 channelled-triangular : involucre of I to 3 brownish scales: spikelets 2 to 5 on 

 short tomentose-scabrous slightly nodding rays : akene linear-oblong, broadest 

 above. Cold bogs across the continent in the northern tier of States. 



2. E. polystachyum, L. Stouter : leaves linear, fiat or barely chan- 

 nelled below: involucre more conspicuous, 2 or 3-leaved: spikelets more numerous 

 and larger, upon longer nodding usually smooth rays : akene broader, obovate. 

 From Colorado northward, and thence eastward across the continent ; also in 

 Oregon. 



4. HEMICARPHA, Nees. 



Distinguished from Scirpus chiefly by the minute hyaline bractlet between 

 the flower and the axis. Style 2-cleft. Low setaceous annuals, with flattened 

 stems, somewhat leafy at base. 



1. H. SUbsquarrosa, Nees. Stems numerous, tufted, 1 to 6 inches high, 

 brown-sheathed at base, with 1 or 2 very short filiform leaves : principal invo- 

 lucral bract continuous with the stem, the others much smaller or none : 

 scales brown, tipped with a short recurved point. From California to New 

 Mexico and Colorado and eastward through the Atlantic States. 



5. ELEOCHARIS, R. Brown. SPIKE-RDSH. 



Scales closely imbricated all around the rhachis. Perianth of 3 to 9 short 

 retrorsely barbed bristles, rarely none. Style usually 3-cleft, the conical or 



