220 COMrOSIT.K. (cOMrosiTK ia-mii-v.) 



02. SILPHIUM, L. 



Heads niany-flowciTd ; tin; rays numerous, pistillate, fortilc, in a single row. 

 Disk-flowi'is i-yliuiiriral, sterile ; the stylo uiulivitleil. Seales of the involucre 

 leafy, inil)rieateil in several rows ; the innermost smallest, eiiart-like. Keeeptacle 

 small, with linear aeutish chaff. Fertile achenia in 3-4 rows, round or ol)ovate, 

 flat, broadly winged, 2-toothed or cmarginate 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 whorlcd leaves, and large heads of yellow flow- 

 ers in corymi)osc panicles. 



* Stems terete, nearli/ naked: leaves alternate; the lowest large, serrate or varionsli/ 

 loheil, lomj-pelioleJ ; the others small and scattered. 



1. S. laciniatum, K Stem hispid or smooth; leaves veiy rough or hi.s- 

 pid, on clasping petioles, pinnately paited ; the divisions oblong or lanceolate, 

 acute, lobed or toothed ; heads large, spicate or racemose ; scjilcs of the invo- 

 lucre ovate, tapering into a long and spreading point, ciliate ; achenia round- 

 obovate, emarginate. — Varies with the more numerous sessile and chisj)ing 

 leaves less deeply parted. (S. gummiferum, A7/ ) — Prairies of Alabama, and 

 westward. July and August. — Stem C° - 8° high. Lowest leaves 1° - 2° long. 

 Heads l^'-2' in diameter. 



2. S. terebinthinaceum, L. Stem smooth, naked above ; leaves rough- 

 hairy, undivided, cordate-oval or oblong, coarsely serrate, on slender petioles ; 

 heads small, loosely panicled ; scales of tiie involucre oval or obovate, obtuse, 

 smooth ; achenia obovate, cmarginate or 2-toothed. (S. pinnatifidum. Ell., 

 leaves ]);nnatifi(l.) — Open woods in the western districts of Georgia, and west- 

 ward. July -Sept. — Stem 4° -8° high. Radical leaves 2° long. Heads 1' 

 wide. 



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, obtnse ; achenia roundish, 

 deeply emarginate; rays 6- 10. (S. terebinthinaceum, £■//., leaves reniform, an- 

 gul.irly toothed or lobed.) — Var. MiCH.vuxii, Torr. & Gray. Leaves deeply 

 pinnatifid or tcrnately divided ; the divisions lobed or toothed. — Var ovatifo- 

 LU'M, Torr. & Gray. Leaves ovate, angularly toothed. — Sandy open woods, 

 Florida to North Carolina. July - Sept — Stem 3° - 6° high. Leaves 6' - 12' 

 long. Heads ^' in diameter. 



* * Stems leafy : leaves undivided, alternate, opposite, or whorled. 

 •t- Stems terete. 



4. S. trifoliatum, L. Stem smooth; leaves rough, lanceolate, slightly 

 serrate, on short biistly petioles ; the upper ones altemate or opposite ; the lower 

 3 -4 in a whorl ; heads small, loosely panicled ; scales of the involucre ovate or 

 oval, fringed on the margins ; achenia oblong-obovate, 2-toothed. (S. ternatum 

 and S. atropurpureum, Wilhl.) — Open woods along the mountains of Georgia, 

 and northward. July - Sept. — Stem 4° - 6° high. Leaves 4' - 6' long. 



5. S. Asteriscus, L. Stem smooth or hirsute ; leaves rough, opposite or 

 altemate, or the lower ones sometimes 3 in a whorl, lanceolate or oblong, toothed. 



