270 COMPOSITE. (COMPOSITE FAMILY.) 



J. P. Uved&lia, !< Roughish-hairy, stout (4 -10 high); leaves broadly 

 ovate, angled and toothed, nearly sessile ; the lower palmately lobed, abruptly 

 narrowed into a winged petiole ; outer involucral scales very large ; rays 10-15, 

 linear-oblong, much longer than the inner scales of the involucre, yellow; achenes 

 strongly striate. Rich soil, W. New York and N. J. to Mo., and southward. 



37. SILPHIUM, L. ROSIN-WEED. 



Heads many-flowered, radiate ; rays numerous, pistillate and fertile, their 

 broad flat ovaries imbricated in 2 or 3 rows ; disk-flowers apparently perfect, 

 but with entire style and sterile. Scales of the broad and flattish involucre 

 imbricated in several rows, thickish, broad and with loose leaf -like summits, 

 except the innermost, which resemble the linear chaff of the flat receptacle. 

 Achenes broad and flat, dorsally compressed, surrounded by a wing notched 

 at the top, without pappus, or with 2 teeth confluent with the winged margin , 

 the achene and its subtending chaff usually falling together ; those of the disk 

 sterile and stalk-like. Coarse and tall rough perennial herbs, with copious 

 resinous juice, and large corymbose-panicled yellow-flowered heads. (2iA</uoj/, 

 the ancient name of some resinous plant, transferred by Linnaeus to this 

 American genus.) 



# Stem terete, alternate-leaved (root very large and thick). 



1. S. lacini&tum, L. (ROSIN-WEED. COMPASS-PLANT.) Rough-bristly 

 throughout, stem stout (3-12 high), leafy; leaves pinnately parted, petioled 

 but dilated and clasping at the base ; their divisions lanceolate or linear, acute, 

 cut-iobed or pinnatijid, rarely entire; heads few (1 -2' broad), sessile or short- 

 peduncled along the naked summit ; scales ovate, tapering into long and spread- 

 ing rigid points ; achenes broadly winged and deeply notched, 6" long. 

 Prairies, Mich, to the Dakotas, and southward. July. Lower and root-leaves 

 vertical, 12-30' long, ovate in outline; on the wide open prairies disposed to 

 present their edges north and south; hence cajled Compass-Plant. 



2. S. terebinthin&ceum, L. (PRAIRIE DOCK.) Stem smooth, slender 

 (4-10 high), panicled at the summit and bearing several or many, large 

 head*, leafless except toward the base ; leaves ovate and ovate-oblong, some- 

 what heart-shaped, serrate-toothed, thick, rough, especially beneath (1 -2 long, 

 on slender petioles) ; scales roundish, obtuse, smooth; achenes narrowly winged, 

 slightly notched and 2-toothed. Var. PINNAT* FIDUM, Gray, has the leaves 

 deeply cut or pinnatifid, but varies into the ordinary form. Prairies and oak- 

 openings, Ohio and Mich, to Minn., and southward. July - Sept. 



* * Stem terete or slightly 4-angled, leafy ; leaves undivided (not large), some 



opposite. 



3. S. trifoli&tum, L. Stem smooth, often glaucous, rather slender (4-7 

 high), branched above ; stem-teases lanceolate, pointed, entire or scarcely serrate, 

 rough, short-petioled ', in whorls of 3 or 4, the uppermost opposite; heads loosely 

 panicled ; achenes rather broadly winged, and sharply 2-toothed at the top. 

 Dry plains and banks, Penn. to Ohio, and southward. Aug. 



4. S. AsteriSGUS, L. Stem hispid (2 -4 high); leaves opposite, or the 

 lower rarely in whorls of 3, the upper alternate, oblong or oval-lanceolate, roarfte.lt/ 

 toothed, rarely entire, rmigh-hairy, the lower short-petiolod : heads nearly soli- 



