COMPOSITE. (COMPOSITE FAMILY.) 249 



* Stem terete, naked above, alternate-leaved near the base (root very large and thick). 



1. S. laciniatum, L. (Rosin-weed. Compass-Plant.) Rough-bristly 

 throughout; stem stout (3° -6° high), leafy to the top; leaves pinnate/.// parted, 

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

 acute, cut-lobed or pinnatijid, rarely entire; heads few (1'- 2' broad), somewhat 

 racemed; scales of the involucre, ovate, tapering into long and spreading rigid points ; 

 achenia broadly winged and deeply notched. — Prairies, Michigan and Wiscon- 

 sin, thence southward and westward. 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 called Compass-Plant. 



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

 (4°-10° high), panicled at the summit and bearing many (small) heads, leafless 

 except towards the base ; leaves ovate and ovate-oblong, somewhat heart-shaped, 

 serrate-toothed, thick, rough, especially beneath (1° - 2° long, on slender petioles) ; 

 scales of the involucre roundish, obtuse, smooth ; achenia narrowly winged, slightly 

 notched and 2-toothed. — Var. pinnatifidum has the leaves deeply cut or pin- 

 natifid, but varies into the ordinary form. — Prairies and oak-openings, Ohio 

 and Michigan to Wisconsin and southward. July- Sept. 



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



3. S. trifoliatum, L. Stem smooth, often glaucous, rather slender (4°- 6° 

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

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

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

 Dry plains and banks, W. New York to Wisconsin and southward. Aug. 



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

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

 rarely entire, rough-hairy; heads nearly solitary (large); achenia obovate, 

 winged, 2-toothed. — Dry sandy soil, Virginia and southward. 



5. S. integrifolium, Michx. Stem rough, rather stout (2° -4° high), 

 rigid, 4-angular and grooved; leaves all opposite, rigid, lanceolate-ovale, entire, 

 tapering to a sharp point from a roundish heart-shaped and partly clasping base, 

 rough-pubescent or nearly smooth, thick (3' - 5' long) ; .heads in a close forking 

 corymb, short-peduncled ; achenia broadly winged, deeply notched. — Var. 

 l2gve has the stem and leaves smooth or nearly so. — Prairies, Michigan to 

 Wisconsin and southward. Aug. 



* * * Stem square: leaves opposite, connate (thin and large, 6' -15' long). 



6. S. perfoliatum, L. (Cup-Plant.) Stem stout, often branched above 

 (4° -8° high) ; leaves ovate, coarsely toothed, the upper united by their bases 

 and forming a cup-shaped disk, the lower abruptly narrowed into winged petioles 

 which are connate by their bases ; heads corymbose ; achenia winged and vari- 

 ously notched. — Rich soil along streams, Michigan to Wisconsin, and south- 

 ward : common. Also escaped from gardens eastward. July. 



28. PARTHEtflUM, L. Parthenium. 



Heads many-flowered, inconspicuously radiate ; the 5 ray-flowers with very 

 short and broad obcordate ligules not projecting beyond the woolly disk, pistil- 



