500 CYPERACEjE. (SEDGE FAMILY.) 



obovate, mucronate, plano-convex. Our plant appears constantly to have a 2- 

 cleft style, and the scales often a little downy on the back, and is S. validus, VahL 

 & S. acutus, Muhl. Fresh-water ponds and lakes; common. July. Culm 

 as thick as the finger at the base, tipped with an erect and pointed involucral 

 leaf, which is shorter or longer than the panicle. (Eu.) 



8. S. debilis, Pursh. Culms slender (6' -12' high), striate, tufted, from 

 fibrous roots, leafless, or 1-leaved at the base ; spikes ovate, few (1-8) in a sessile 

 cluster, appearing deeply lateral by the prolongation of the 1-leaved involucre; 

 scales round-ovate (greenish-yellow) ; style 2-3-cleft; bristles 4-6, longer than 

 the obovate plano-convex or lenticular shining minutely dotted achenium, or 

 rarely obsolete. (J) Low banks of streams, Massachusetts to Michigan, Illi- 

 nois, and southward. Aug. 



# # # Spikes clustered and mostly umbeUed, plainly terminal, many-flowered : involu- 

 cre leafy : culm leafy, triangular, and with closed joints below (style 3-clefl). 

 *- Scales of the large spikes awl-pointed, lacerate-3-cleJl at the apex. 



9. S. ilia i it i in us, L. (SEA CLUB-RUSH.) Leaves flat, linear, as long 

 as the stout culm (l-3 high), those of the involucre 1-4, very unequal; 

 spikes few - several in a sessile cluster, and often also with 1-4 unequal rays 

 bearing 1-7 ovate or oblong-cylindrical (rusty brown) spikes ; achenium obovate- 

 orbicular, much compressed, fiat on one side, convex or ol)tuse-angkd on the other, mi- 

 nutely pointed, shining, longer than the 1-6 unequal and deciduous (sometimes 

 obsolete) bristles. Var. MACROSTACHYOS, Michx. (S. robustus, Pursh.) is a 

 larger form, with very thick oblong or cylindrical heads, becoming l'-lf' long, 

 and the longer leaf of the involucre often 1 long. Salt marshes ; common on 

 the coast, and near salt springs (Salina, New York), &c. Aug. Heads beset 

 with the spreading or recurved short awns which abruptly tip the scales. (Eu.) 



10. S. fluviii tills. (RIVER CLUB-RUSH.) 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, bearing 1-5 ovate or oblong-cylindrical acute heads ; acheni- 

 um obovate, sharply and exactly triangular, conspicuously pointed, opaque, scarcely 

 equalling the 6 rigid bristles. (S. marit., var. ? fluviatilis, Torr., excl. syn. Ell.) 

 Borders of lakes and large streams, W. New York to Wisconsin and Illinois. 

 July, Aug. Culm very stout, sharply triangular, 3 - 4 high. Leaves rough- 

 ish on the margin, like the last; those of the umbel 3-7, the largest l-2 

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

 to li' long, paler and duller than in No. 9 ; the scales less lacerate and the awns 

 less recurved ; the fruit larger and very different. 



*- f- Scales of tJie small compound-umbelled and clustered heads mucronate-tipped. 



11. S. -sylViitiCllS, L. Cuhn leafy (2 -5 high) ; leaves broadly linear, 

 flat, rough on the edges ; umbel cymose-decompound, irregular ; the numerous 

 spikes clustered (3 - 10 together) in dense heads, ovoid, dark lead-colored or olive- 

 green turning brownish ; bristles 6, downwardly barbed their whole length, straight, 

 scarcely longer than the convex-triangular achenium. Low grounds, N. New 

 England and northward. Var. ATR^VIRENS (S. atrovirens, Muhl.) is a form 

 with the spikes (10-30 together) conglomerate into denser larger heads. Wet 



