220 | COMPOSIT#. (COMPOSITE FAMILY.) 
32. SILPHIUM, L. 
Heads many-flowered ; the rays numerous, pistillate, fertile, in a single row. 
Disk-flowers cylindrical, sterile ; the style undivided. Scales of the involucre 
leafy, imbricated in several rows; the innermost smallest, chaff-like. Receptacle ER 
small, with linear acutish chaff. Fertile achenia in 3-4 rows, round or obovate, 
flat, broadly winged, 2-toothed or emarginate at the apex ; the sterile ones slen- 
der. Pappus none, or represented by the two teeth of the achenia. — Tall resinous 
herbs, with alternate opposite or whorled leaves, and large heads of yellow flow- 
ers in corymbose panicles. 
* Stems terete, nearly naked: leaves alternate; the lowest large, serrate or variously 
lobed, long-petioled ; the others small and scattered. s 
1. S. laciniatum, L. Stem hispid or smooth; leaves very rough or his- ; 
pid, on clasping petioles, pinnately parted; the divisions oblong or lanceolate, ——— 
acute, lobed or toothed ; heads large, spicate or racemose ; scales of the invo = — 
lucre ovate, tapering into a long and spreading point, ciliate ; achenia round- - 
obovate, emarginate. — Varies with the more numerous sessile and clasping 
leaves less deeply parted. (S. gummiferum, Ell.) — Prairies of Alabama, and - 
westward. July and August. — Stem 69 — 89 high. Lowest leaves 19 - 29 long. 
Heads 13! - 2! in diameter. 
2. S. terebinthinaceum, L. Stem smooth, naked above ; leaves rougl- 
hairy, undivided, cordate-oval or oblong, coarsely serrate, on slender petioles; 
heads small, loosely panicled; scales of the involucre oval or obovate, obtuse, 
smooth; achenia obovate, emarginate or 2-toothed. (S. pinnatifidum, Ell, 
leaves pinnatifid.) — Open woods in the western districts of Georgia, and west- 
ward. July- Sept. — Stem 49-89 high. Radical leaves 29 long. Heads! 
wide. j 
3. S. compositum, Michx. Smooth; leaves cordate-ovate or reniform, 
angularly toothed or variously lobed, long-petioled ; heads small, corymbosely 
panicled ; scales of the involucre obovate or oblong, obtuse ; achenia roundish, 
deeply emarginate; rays 6-10. (S. terebinthinaceum, Ell, leaves reniform, at 
gularly toothed or lobed.) — Var. Micnauxri, Torr. & Gray. Leaves deeply 
pinnatifid or ternately divided; the divisions lobed or toothed. — Var. ovATIFÓ- 
LIUM, Torr. & Gray. Leaves ovate, angularly toothed. — Sandy open 
Florida to North Carolina. July- Sept. — Stem 39-69 high. Leaves 6-1? 
long. Heads j'in diameter. - " 
* * Stems leafy : leaves undivided, alternate, opposite, or whorled. 
Bases + Stems terete. puc 
. ^. S. trifoliatum, L. Stem smooth; leaves rough, lanceolate, slightly — 
serrate, on short bristly petioles ; the upper ones alternate or opposite ; the — o 
3-4 in a whorl; heads small, loosely panicled ; scales of the involucre ovate F — 
v: fringed on the margins; achenia oblong-obovate, 2-toothed. (S. ternatum 
a D. 
