270 COMPOSITE, (composite family.) 



2. p. Uved^lia, L. Roughish-hairi/, stout (-^-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 ; raijs 10-15, 

 linear-ohlonrj, 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. SI LP HI UM, L. Rosix-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. {ZiKcpiov, 

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

 American genus.) 



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



1. S. laciniatum, L. (Rosix-weed. Compass-Plaxt.) Rough-bristly 

 throug'iout, stem stout (3-12° high), leafy; leaves pinnately parted, petioled 

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

 cut-lohed 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, 12t30' long, ovate in outline ; on the wide open prairies disposed to 

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



2. S. terebinthinaceum, L. (Prairie Dock.) Stem smooth, slender 

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

 headg, 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. pixxatifidum, 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. trifoliatum, L. Stem smooth, often glaucous, rather slender (4-7° 

 high), branched above ; stem-Zeaj^es lanceolate, pointed, entire or scarcely serrate, 

 rough, short-petioled, in ivhorls of 3 or 4, the uppermost opposite; heads looselv 

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

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



4. S. Asteriscus, L, Stem hispid (2 - 'i° high) ; leaves opposite, or the 

 lower rarely in whorls of 3, the upper alternate, oblong or oval-lanceolate, coarsely 

 toothed, rarely entire, rough-hairy, the lower short-petioled ; heads nearly soli- 



