210 COMPOSITE, (composite family.) 



like. — Coarse and tall rongh perennial herbs, with a copious resinous jnice, 

 and large corymbosc-panicled yellow-flowered heads. (SiX^iov, the ancient 

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

 by Linnaeus to this American genus.) 

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



1. S. laciniatuin, 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 pinnatijid, 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 Wisconsin, thence 

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

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

 and hence called Compass-Plant. 



2. S. tcrebintliinaceum, 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. PiNNATfFiruM 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. trifoliiitum, L. Ste7n smooth, often glaucous, ia,ther slenier {4° -6° 

 high), branched above, stem-Zeowes lanceolate, pointed, entire or scarcely seiTate, 

 rough, short-petioled, in whorls of 3 or i, 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. Asteriscns, 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, the upper sessile ; heads nearly solitary (large) ; ache- 

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



5. S. integrifolium, Michx. Stem rough, xathex 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-podunclcd ; achenia broadly winged and deeply notched. — Var. 

 LiEVE 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. perfoliatUHl, 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. 



