ORDEE 70. COMPOSITE. 441 



leafy, the inner chaffy ; receptacle flat, chaffy ; achenia of the ray ob- 

 compressecl, obovate, each embraced by a chaff-scale ; achenia of the 

 disk abortive; pappus a small, 2 to 3-toothed crown. 2 A little pros- 

 trate herb, with opposite Ivs. and solitary, pedunculate, bright yellow 

 vernal fls. 



C. Virginiamim L. In rich shady soils, Md. to 111., common southward to tho 

 Gulf. One of the earliest flowers of spring. Plant flat on the ground, hirsute, 

 at first acaulescent, at length caulescent and ascending. Lvs. ovate, tapering to 

 a petiole, crenate. Kays expanding 7 to 9". Feb. May. 



41. SIL'PHIUM, L. ROSIN-WEED. (The ancient name of some 

 resinous plant.) Heads many-flowered; ray-flowers numerous, in 2 or 

 3 rows, fertile, outer row ligulate ; disk-flowers sterile ; involucre cam- 

 panulate, scales in several series, leafy and spreading at summit ; recep- 

 tacle small, flat, chaffy ; achenia broad, flat, obcompressed, crowned 

 with a 2-toothed pappus. 2|! Stout, coarse, resinous herbs. Hds. large. 

 Fls. yellow. 



* Stem nearly leafless, scape-like. Lvs. very large, alternate, mostly radical TTos. 1 3 



* Stem leafy. Leaves vcrticillate in whorls of 3s, rarely 4s Nos. 4, 5 



Leaves opposite, rarely the highest scattered Nos. 5 7 



Leaves alternate (the lowest opposite or verticillate or alternate) No. 3 



Leaves connute-perfoliatc .No. 9 



1 S. laciniatniri L. POLAR PLANT. Very rough, with white, hispid hairs; Ivs. 

 alternate, pinnately parted, lower petiolate, segments sinuate-lobed or entire ; 

 hds. spicate, distant; scales ovate, appendaged and squarrous at apex. Western 

 States to Tex., producing columns of smoke in the burning prairies by its co- 

 pious resin. Stem 3 lOf high. Lower Ivs. 1 2f long, much divided, resem- 

 bling those of some thistles. Heads 4 8, very large, with large, yellow rays. 

 Jl. Sept. 



2 S. terebinthinacemn L. PRAIRIE BURDOCK. St. and ped. glabrous ; Ivs- 

 mostly radical, ovate and ovate-oblong, cordate, dentate-serrate, obtuse, scabrous, on 

 long petioles ; hds. few, paniculate ; scales roundish and oval, glabrous, rays about 

 20. Prairies, Western and Southern States. Plant exuding resin. Stem 4 8f 

 high, nearly naked and simple. Leaves 1 2f long, '7 16' wide. Involucre 

 globous. Hds. 1' diam., rays 1' long. Achenia narrowly 2-winged. Jl. Sept. 



j3. PINNATIFIDUM. Lvs. more or less deeply lobed or pinnatifid. Prairies, etc., 

 with the other form. (S. pinnatilidum Ell.) 



3 S. compositum MX. Glabrous throughout; st. slender, almost naked, glau- 

 cous; Ivs. radical, on long petioles, deeply sinuate-pinnatifid, the segments sinuate- 

 lobed or toothed ; hds. corymbed, on long peduncles; scales oval, obtuse; ach. 

 roundish-obovate ; rays about 10. Barrens, N. Car. to Fla. (Feay). St. 3 to 6f 

 high. Hds. 7" diam., about 10-rayed, rays about as long (4'') as the involucre. 

 June. Aug. 



/?. RENIFORME. Lvs. roundish or reniform, cordate, slightly sinuate-lobed or 

 toothed. Upper districts of Ga. and Car. 



4 S. trifoliatum L. St. glabrous and often glaucous, terete or 6-sided ; cauline( 

 Ivs. lanceolate, acute, scabrous above, smooth below, remotely dentate, on very 

 short petioks, verticillate in 3s or 4s ; upper ones opposite; hds. loosely cymose, 

 on rather long peduncles ; scales broadly ovate, rather obtuse, smooth ; ach. oval, 

 with 2 short teeth. Dry woods and prairies, Ohio and Southern States. Stem 

 4 6f high. Leaves 4 G' by 12". Kays 12 1C, expanding about 2^'- Ach. 

 3 to 4" long, 2 to 3" wide. Aug., Sept. 



5 S. iiitegrifolium MX. Scabrous ; st. quadrangular, striate, simple ; Ivs. oppo- 

 site, sessile, ovate-lanceolate, entire or slightly dentate ; hds. in a close corymb; 

 scales 'squarrous ; ach. roundish, broadly ivinged, with 2 long teeth. Western States 

 S. to Ga. Stem very rigid, 3 7f high. Leaves rigid, broad and clasping at 

 base. Heads middle-size. Kays 1220. 1' in length. Ach. 4 to 5" long, 4 ' 

 wide. Jl., Aug. 



