210 composite, (composite family.; 



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

 and large eorymbose-panicled yellow-flowered heads. (2i\cpt.Qv, the ancient 

 name of a plant which produced some gum-resin (assafcetida?), was transferred 

 by Linnaeus to this American genus.) 



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



1. S. EaciiiiiyiBikti, 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- 

 lobed or pinnatifid, rarely entire ; heads few (1'- 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. tercMiitliiiiitccum, 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, serrate-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. i>inn t ati'fidum 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 o? slightly 4-angled, leafy : leaves undivided (not large). 



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

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

 rough, short-pet iolcd, in ichorls of 3 or A, 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. AsterisciIS, L. Stem hispid (2° -4° high); leaves opposite, or the 

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

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

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



5. S. integrifolilllll, 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-pubeseent or nearly smooth, thick (3' - 5' long) ; heads in a close forking 

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

 lmye 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 aloDg streams, Michigan to "Wisconsin, and 

 southward ; common. July. 



