COMPOSITE. (COMPOSITE FAMILY.) 249 



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



1. S. laeiniktum, L. (ROSIN-WEED. COMPASS-PLANT.) Rough-bristly 

 throughout; stem stout (3 -6 high), leafy to the top; leaves pinnately parted, 

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

 acute, cut-lobed or pinnatifid, rarely entire; heads few (l'-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. terebinthinaceum, 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. piNNAxfriDUM 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. trifolitlim, L. Stem smooth, often glaucous, rather slender (4- 6 

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

 rough, short-petioled, 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 tootlied, 

 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-ovate, 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. 

 L&VE 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. perfoli&tum, 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. PABTHilNIUM, 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- 



