210 COMPOSITE. (COMPOSITE FAMILY.) 



like. Coarse and tall rough perennial herbs, with a copious resinous juice, 

 and large corymbose-panicled yellow-flowered heads. (Si'X^tov, the ancient 

 name of a plant Avhich produced some gum-resin (assafoetida ?), was transferred 

 by Linnaeus to this American genus.) 



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



1. S. laciiiiatuiii, L. (ROSIN-WEED. COMPASS-PLANT.) Very rough- 

 bristly throughout; stem stout (3 -6 high) ; leaves pinnately parted, petioled but 

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

 lobedor pinnatifid, rarely entire; heads few (l'-2' broad), somewhat raccmed ; 

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

 broadly winged and deeply notched. Prairies, Michigan and Wisconsin, thence 

 southward and westward. July. Lower leaves 12' -30' long, ovate in outline; 

 on the wide open prairies, said to present their edges uniformly north and south, 

 and hence called Compass-Plant. 



2. S. terebillthinaceuni, L. (PRAIRIE DOCK.) Stem smooth, slen- 

 der (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, seirate-toothed, thick, rough, especially beneath (l-2 long, and on 

 slender petioles) ; scales of the involucre roundish, obtuse, smooth; achenia nar- 

 rowly winged, slightly notched and 2-toothed. Var. PINNATLFIDUM has the 

 leaves deeply cut or pinnatifid, but varies into the ordinary form. Prairies 

 and oak-openings, Ohio to Wisconsin and southward. July -Sept. 



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



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

 high), branched above, stem-/eaves 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. AsteriscilS, L. Stem hispid (2 -4 high); leaves opposite, or the 

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

 rarely entire, rough-hairy, the upper sessile ; heads nearly solitary (large) ; ache- 

 aia obovate, winged and 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 and deeply notched. Var. 

 LJEVE 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 variously notched. Rich soil along streams, Michigan to Wisconsin, and 

 southward ; common. July. 



