Silphium. COMPOSITE. 241 



■+- -f— Leaves rather few on the slender stem, the lower slender-petioled, often alternate : akenes 

 with the broad wings of the preceding. 



S. gracile, Gray. Hispidulous: stem 12 to 30 inches high, rather naked, terminated by 

 solitary or few mostly long-peduncnlate heads : leaves membranaceous, ovate-oblong or ob- 

 long-lanceolate, acute at both ends, denticulate; radical and lower cauline ample (5 to 9 

 inches long) ; upper cauline from 2 inches to half-inch long : involucre of nearly equal and 

 rather few oblong bracts : akenes orbicular or very broadly oval, broadly winged, and with 

 a comparatively shallow notch. — Proc. Am. Acad. viii. 653. — Prairies of Middle Texas, 

 Drummond, Lindheimer, Hall, &c. Sometimes the leaves are all alternate and the petioles 

 of the one or two principal cauline 2 or 3 inches long, equalling the blade. 



-* — ^ — -i — Leaves numerous on the stem, varying from opposite to alternate or the middle ones 

 verticillate, only upper and alternate ones (if any) strictly sessile by a broad base : akenes with 

 narrow wings and a comparatively shallow open notch ; awn-like pappus-teeth usually evident 

 and not rarely parth' separate from the wing. 



S. Asteriscus, L. Stem 2 to 4 feet high, commonly hispid : leaves from ovate-oblong to 

 oblong-lanceotete, coarsely and irregularly dentate or serrate, or some entire, scabro-hispid- 

 ulous or hispid, all the upper not rarely alternate, seldom any verticillate ; upper commonly 

 sessile by a rounded or partly clasping base ; lower short-petioled : heads solitary or few on 

 leafy branches : involucre foliaceous and squarrose (half-inch high), hirsute or hispidulous : 

 akenes obovate-oval. — Spec. ii. 920 (Dill. Elth. t. 37, f. 42); Michx. PI. ii. 146; DC. Prodr. 

 v. 512 ; Torr. & Gray, PI. ii. 278. — Dry sandy soil, common from Virginia and Tennessee 

 to Plorida and Louisiana. 



Var. laevicatile, DC, 1. c. Stem smooth and glabrous, either throughout or up to the 

 branches. — Torr. & Gray, 1. c. S. scabrum, Walt. Car. 217. S. reticulatum, Mcench, Meth. 

 607, fide syn. L. S. Asteriscus, var. scahrum, Nutt. Gen. ii. 183. S. dentatum, Ell. Sk. ii. 468 ; 

 Torr. & Gray, 1. u. S. lanceolatum, Nutt. Trans. Am. Phil. Soc. vii. 341, a narrow-leaved 

 form. S. Asteriscus, var. dentatum, Chapm. PI. 221. — S. Carolina to Georgia and Alabama. 



S. trifoliatum, L., 1. c. Stem 4 to 7 feet high, very smooth and glabrous, terminated by 

 naked corymbiform panicles of numerous usually slender-peduncled heads : leaves lanceo- 

 late, varying to oblong ovate, and from entire to sparsely serrate, from almost glabrous and 

 smooth to scabrous or hispidulous-puhescent, seldom alternate, a part of them usually 3-4- 

 nately verticillate, commonly acute at base and the upper subsessile, lower tapering into 

 margined petioles : involucre somewhat campanulate, narrower and usually smaller than in 

 the foregoing ; the bracts hardly foliaceous, smooth and glabrous, except the eiliate margins : 

 akenes broadly obovate-oval. — Hook. Bot. Mag. t. 3355 ; Torr. & Gray, 1. c. S. trifoliatum, 

 ternatum, & atropurpureum, Retz in Willd. Spec. iii. 2333. 5. ternifolium, Michx. PI. ii. 146. 



• — Dry woodlands, Penn. and Ohio, and through the upper country to Alabama. 



Var. latif Olium. Stem 2 to 4 feet high : leaves broader, seldom more than opposite : 

 heads fewer and broader. — S. Icevigatum, Ell. Sk. ii. 465 (perhaps Pursh, PL ii. 578, but his 

 character points to S. integrifolium) ; Torr. & Gray, 1. c. — W. Georgia, Alabama, and low 

 country of S. Carolina ; and broad-leaved northern forms are Bimilar. 



# # # Stem terete, almost leafless and scapiform, bearing a loose panicle of slender pedunculate 

 heads: involucre nearly hemispherical, of rounded mostly erect and coriaceo-herbaceous bracts: 

 radical leaves ample, long-petioled, cordate at base: cauline when present all alternate and 

 slender-petioled : herbage almost glabrous and smooth, or the leaves hispidulous and papillose- 

 scabrous. (True Rosin-Weeds.) 



S. COmpositum, Michx. Stem slender, 2 to 6 feet high, commonly glaucous : radical 

 leaves of roundish-cordate or reniform or more ovate circumscription, 6 to 12 inches long or 

 broad : heads small and numerous : involucre a third or rarely half inch high : rays small 

 and scattered, 4 lines long : akenes roundish-obovate and with wing broadened above, so as to 

 form a deep notch, with which the two subulate pappus-teeth are confluent, sometimes nar- 

 rowly winged so that the summit is barely emarginate and minute pappus-teeth nearly free. 

 — Torr. & Gray, PI. ii. 276. The first-described form (var. Michauxii, & var. ovatifolium, Torr. 

 & Gray,l. c.) has the leaves varying from deeply sinuate-pinnatifid to pinnately or somewhat 

 temately divided into 3 to 7 divisions, which are again sinuate-lobed ; for this the specific 

 name is appropriate, being S. compositum, Michx. PI. ii. 145 ; Ell. 1. c. ; DC. 1. c, and S. la- 

 ciniatum, Walt. Car. 217, not. L. S. nudicaule, M. A. Curtis in Bost. Jour. Nat. Hist. i. 127, 



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