192 



CYPERACEAE (sedge FAMILY) 



290. 8. validus. 



17. S. vdlidus Vahl. (Great B.) Rootstook stout, scaly, horizontal ; 

 culm 0.5-2.5 rii. high, 0.8-2.5 cm. thick at base, soft, light green; basal 



sheaths soft, with soon lacerate hyaline margin; decom- 

 pound panicle lax, the rays 1-6 cm. long, slender and 

 flexuous ; bractlets brownish, pubescent at tip, fimbriate 

 dilate, with strongly excurrent midrib ; spikelets solitary or 

 in glomerules of 2-5, rnfescent, ovoid, acutish, 5-10 mm. 

 long ; scales suborbicular, a little pubes- 

 cent on the back, ciliate, mucronate ; style 

 2-cleft ; achene fuscous or dull black 

 when ripe, broad-obovoid, plano-convex, 

 mucronate, 1.3-1.5 mm. broad. (iS. lacus- 

 tris, mostly of Am. auth., not L.) — Mar- 

 gins of ponds and quiet streams. July, 

 Aug. Fig. 290. 



18. S. occidentHlis (Wats.) Chase. Similar; the culms 

 harder, olive-green ; basal sheaths firmer, the margins becom- 

 ing fibrillose ; panicle compound, the rays 0.5-5 cm. long, 

 stiff; bractlets red-spotted, viscid at tip, lacerate-fimbriate, 

 abruptly mucronate ; spikelets mostly in glomerules of 2-7, 

 rarely solitary, drab to reddish-brown, subcylindric, 1-2 cm. jg; g occldentalis 

 long ; scales oblong-ovate, aristate, red-dotted, viscid above ; ' ' 



achene biconvex, 1.7-1.9 mm. broad. — Lake-borders, Nfd. to B. C, s. to Mass., 

 N. Y., Great Lakes, Mo., etc. Aug., Sept. Fig. 291. 



19. S- heterochaStus Chase. Similar ; the culms slender, rarely 1 cm. thick 

 at base, pale green ; panicle compound, the suberect very slender rays 1-9 cm. 



long ; bractlets pale, aristate-acuminate, glabrous; spike- 

 lets solitary, ellipsoid, 8-14 mm. long, pale brown ; scales 

 ovate-oblong, exceeding the achenes, emarginate, short- 

 aristate, slightly red-dotted, glabrous, with erose-flmbriate 

 margins; style S-cleft; bristles 

 fragile, 2-4 ; achene greenish 

 or yellowish, 2.5-3 mm. long, 

 1.7-2 mm. broad. — Marshes 

 and sheltered shores, e. Mass. 

 and Vt. to 111., Neb., and Ore. 

 July, Aug. Fig. 292. 



20. S. fluvidtilis (Torr.) 

 Gray. (Rivek B.) Culm very 

 stout, 1-1.5 m. high ; leaves 

 flat, broadly linear (0.7-2 cm. wide), tapering gradu- 

 ally to a point, the upper and those of the very long 

 involucre very much exceeding the compound umbel ; 

 rays 5-12, elongated, recurved-spreading, each bearing 

 1-5 ovoid to cylindrical acute pale-brown spikelets 

 (1.5-4 cm. long) ; scales slightly lacerate, the awns 

 much exceeding the cleft tip ; 

 achene obovoid, sharply and 

 exactly triangular, conspicu- 

 ously pointed, opaque, about 

 equaling the 6 rigid bristles. 



— Borders of lakes and large streams, e. Mass. and 

 Vt. to D. C, w. to Minn., Kan., etc. July-Sept. 

 Fig. 29.3. 



21. S. robiistus Pursh. Leaves flat, green, 4-10 mm. 

 broad, as long as or longer than the stout culm (0.7- 

 1.2 m. high), those of the iniiolucre 3 or 4, very unequal, 

 the longest 2.5-4 dm. long; spikelets \-\li, rufescent, 

 ovoid to cylindric, 1.5-3 cm. long, 6-12 mm. thick, 

 2SW. 8. robustus. some sessile, the others borne on short (2-6 cm. long) 



S. heterochaetus. 



293. S. fluviatilis. 



