564 CYPERACE^E. (SEDGE FAMILY.) 



scales soon recurved ; achenium obovate-orbicular, compressed, flat on one side, con- 

 vex or obtuse-anyled on the other, minutely pointed, shining, longer than the 1 - 6 un- 

 equal and deciduous (sometimes obsolete) bristles. Var. MACROSTACHYOS, 

 Michx. (S. robiistus, Pursh) is a larger form, with very thick oblong-cylindri- 

 cal heads, becoming !'-!' long, and the longer leaf of the involucre often 

 1 long. Salt marshes: common on the coast, and near salt springs in the 

 interior (W. New York, &c.). (Eu.) 



16. S. fluviatilis, Gray. (RIVER C.) Leaves flat, broadly linear (' or 

 more wide), tapering gradually to a point, the upper and those of the very long 

 involucre very much exceeding the compound umbel ; rays 5-9, elongated, recurved- 

 spreading, each bearing 1-5 ovate or oblong-cylindrical acute heads ; achenium 

 obovate, sharply and exactly triangular, conspicuously pointed, opaque, scarcely equal- 

 ling the 6 rigid bristles. (S. maritimus var. ? fluviatilis, Torr., excl. syn.) 

 Borders of lakes and large streams, W. Vermont to Penn., Wisconsin and 

 Illinois. Culm very stout, sharply triangular, 3 - 5 high. Leaves roughish 

 on the margin, like the last; those of the umbel 3-7, the largest 1 - 2 long. 

 Principal rays of the umbel 3' - 4' long, sheathed at the base. Heads paler 

 and duller than in the preceding ; the scales less lacerate, and their awns less 

 recurved , the fruit larger and very different. 



i- *- Spikes very numerous, small, V-3' long ; their scales mucronate-pointed or 

 blunt : umbel-like cymose panicle irregular, compound or decompound : culm 

 2 - 5 high, unusually leafy ; leaves broadly linear, green and rather soft, rough 

 on the edges : bristles of the perianth very slender, often more or less tortuous and 

 naked below: transition to Trichophorum. 



17. S. SylvaticuS, L. Spikes lead-colored, clustered 3-10 together at the 

 end of the mostly slender ultimate divisions of the open decompound panicle, ovoid 

 or lanqe-ovate, 2" long ; scales bluntish ; biistles 6, downwardly barbed through- 

 out, rather exceeding the triangular short-pointed achenium ; style 3-cleft. 



Along brooks, E. Mass., W. Boott, to Albany, N. Y., C. H. Peck. (Eu.) 



18. S. microcarpus, Presl. Like No. 17, but earlier, and with rather 

 smaller heads, blunter scales, 2 stamens, a 2-cleft style, 4 bristles, and obovate- 

 lenticular achenium. (S. lenticularis, Torr.) Near Boston, W. Boott, to New 

 Hampshire, Oakes, frc., and N. W. 



19. S. atr6virens, Muhl. Leaves somewhat more rigid ; spikes dull 

 greenish-brown, densely conglomerate (10-30 together) into close heads, these also 

 usually densely clustered in a less compound panicle ; scales pointed ; bristles 

 sparsely and strongly downwardly barbed above the middle, naked below, nearly 

 straight, as long as the conspicuously pointed and obovate-oblong triangular 

 achenium. (S. sylvatictis, var. atrovirens, Ed. 2., Wet meadows and bogs, 

 New England to Kentucky and northward : common. 



20. S. polyph^llus, Vahl. Culm usually more leafy ; spikes yellow-brown, 

 ovate, becoming cylindrical, clustered 3-8 together in small heads on the short 

 ultimate divisions of the open decompound umbel ; scales mucronate ; bristles 6, 

 usually twice bent, sqfl-barbed towards the summit only, about twice the length of 

 the achenium. (S. exaltatus, Pursh. S. briinneus, Muhl.) Swamps and 

 shady borders of ponds, W. New England to Illinois, and common southward. 



