240 COMPOSIT.E. Acanthospermum. 



A. hiJmile, DC. Larger, commonly erect, hirsute : leaves wing-petioled or sessile by a 

 cuneate base: fructiferous bracts somewhat 3-angled, not grooved, armed (besides the 

 prickles) with one or two long spines from the truncate summit. — A. humile & A. hispidum, 

 DC. 1. c. Melampodium humile, Swartz, Prodr. 114. Cr^ntrospermvni humile. Less. Svn. 

 217. — Ballast-weed, about Philadelphia and New York; naturalized at Pensacola. (Nat. 

 from W. Ind.) 



70. SILPHIUM, L. Rosin-weed. (^CXcjuov, ancient name of an Um- 

 belliferous plant in N. Africa which produced a gum-resin, transferred by Lin- 

 nteus, in his accustomed way, to an American genus.) — Tall and coarse perennials 

 (all of Atlantic U. S.) ; with resinous juice, thick roots, commonly large leaves, 

 and ample pedunculate heads of yellow flowers (one species with white rays !), 

 produced in summer and autumn. — Torr. & Gray, Fl. ii. 275 ; Benth. & Hook. 



le top : ba^ of the leaJ^s or of their winged petioles cupulate-connate. 



»S. perfoliatum, L. (Cdp-plant.) Stem 4 to 8 feet high, commonly very smooth and 

 glabrous : leaves either smooth or scabrous, sometimes hirsute-pubescent beneath, ovate or 

 the upper ovate-lanceolate (the larger a foot or more long), dentate or denticulate with 

 mucronate teeth ; upper ones united by their broad bases and lower by winged petioles 

 into a perfoliate cup : heads terminating the loosely cymosely disposed flowering branches, 

 on naked peduncles : involucre short-campanulate, half or two-thirds inch high ; outer bracts 

 ovate, from erect to somewhat squarrose-spreading : rays inch long : akenes either with deep 

 or shallow notch, the narrow wings being produced either into very small obsolete or prom- 

 inent triangular teeth. — Spec. ed. 2, ii. 1.301 ; Gouan, Hort. Monsp. 462; Hook. Bot. Ma", 

 t. .3.3.54 ; Torr. & Gray, 1. c. >S. connatum, L. Mant. 574, a form with branches somewhat 

 hispid. S. tetragonum & S. scabrum, Jluiuch, Meth. 606. S. conjunctum, "Willd. Enum. 

 6.33. /S. //ornemanni', Schrad. Hort. Goett. ; DC. Prodr. v. 514. S. en/Mrocna/oH, Bernh. in 

 Spreng. Svst. iii. 630. — Alluvial soil, Michigan and Wisconsin toLTpper Georgia and 

 Louisiana. Common in cultivation ; variable but characterfstic. 



="= * Stem from obtusely quadrangular to terete, leafy : leaves all or some of them opposite, entire 

 or serrate, not connate-perfoliate, 



-1— All but the lower sessile, and either all opposite or the upper pairs occasionally disjoined: 

 akenes with a broad wing and a deep narrow notch: stems 2 to 4 feet high, rigid, very leafy 

 to tlie top. 



' S. integrif olitun, Miciix. Stem smooth or scabrous, sometimes rough-hispid ulous : leaves 

 entire or denticulate, lanceolate-ovate or ovate-lanceolate ; all the upper ones closely sessile 

 by a broad and roundish or subcordate partly clasping base, and tapering from below tlie 

 middle to an acute apex, scabrous above, from nearly glabrous and smooth to cinereous- 

 pubescent beneath, 3 to 5 inches long, commonly of firm texture : heads somewhat corym- 

 bose, nearly all short-peduncled : involucre over half-inch high ; its bracts mostly ovate and 

 spreading : akenes l^roadly obovate, the body 4 lines long, the scarious wing a line or so wi.le, at 

 least toward the summit. — Fl. ii. 146; Torr. & Gray, Fl. ii. 279, hardly of Ell. S.la'vi- 

 gatum, Pursh, as to char. S. sprciosum, Nutt. Trans. Am. Phil. Soc. vii. 341, a very smooth 

 form, the ^■ar. Icrve, Torr. & Gray, 1. c — Prairies, &c., Wisconsin and Illinois to Arkansas 

 and Texas, and possibly to W. Georgia. 



■ S. asperrimum, Hook. Commonly taller: stem rough-hispid: leaves of the preceding 

 but more scabrous: heads generally larger: akenes with broader winas, the triangular 

 apical portions 2 or 3 lines high. — Comp. Bot. Mag. i. 99. S. r«(/»/o, Nutt. Trans. Am. 

 Pliil. ,S,jc. 1. 0. 5. scaberrimitiH, Torr. & Gray, Eh ii. 279, var. y, hardly Ell. — Plains of 

 Arkansas, I>ouisiana, and Texas. 



S. scaberrimum, Ell. Stem and commonly both sides of the leaves hispid : leaves iu 

 remoter pairs, thinner, oblong or ovate, all but the uppermost ratlier coarsely serrate and 

 with n.arrowed or even short petiole-like base (the larger 4 to 6 inches long) ; heads iewcr, 

 more pedunculate : rays inch long : outermost involucral bracts smaller : akenes including 

 broad wing nearly orbicular in outline, hall-inch in diameter. — Sk. ii. 4G2 ; Torr. & Gray, 

 Fl. ii. 279, excl. var. y. — W. Georgia to Louisiana and E. Texas. 



