194 COMPOSITE. (composite family.) 



* $: * * # Leaves none of them heart-shaped; those of the stent, tapering at the base, 

 sessile; involucre imbricated ; the scales of unequal length, with short and narrow 

 oppressed or rather loose greenish tips : heads small or middle-sued: rags white or 

 pale bluish-purple. 



•*- Heads small. (Involucre \' - \' long.) 



18. A. tSlSBMOSsaS, L. Smooth or nearly so, racemosely compound, the 

 scattered heads mostly solitary at the end of the spreading branchlets ; leaves linear 

 or the upper oblong, crowded, entire or slightly serrate, with rough margins ; 

 scales of the closely imbricated involucre linear-spatulate, obtuse, in 4-6 rows. — 

 Thickets, in dry or moist soil; common. — A variable species, l°-3° high, 

 loosely branched, with small leaves, especially the upper, and an inversely con- 

 ical or bell-shaped involucre, with more abrupt green tips than any of the suc- 

 ceeding'. Rays pale purple or blue, larger than in the next. Runs into several 

 peculiar forms. 



19. A. HVftdesCltsiti, L. Smooth or smoothish ; the numerous heads closely 

 racemed along one side of the erect-spreading or diverging branches; leaves 

 lanceolate-linear, elongated, the larger ones remotely serrate in the middle with 

 fine sharp teeth ; scales of the involucre narrowly linear, acute or acutish, imbricated 

 in 3 or 4 rows. — Var. fkagilis has the leaves entire or nearly so, except the 

 lowest, and the heads more scattered. — Moist hanks, &c, very common. — 

 Stems 2° -4° high, bushy: heads very numerous, smaller than in the last. 

 Rays white or nearly so. 



20. A. isslsen', L., Ait. Mare or less hairy, much branched; the branches 

 usually diverging, bearing racemose often scattered heads; leaves lanceolate or ob- 

 long-lanceolate, tapering or pointed at each and, sharply si irate in the middle; 

 scales of the involucre linear, acute or rather obtuse, imbricated in 3 or 4 rows. — 

 Thickets, fields, &c, very common, and extensively variable. — Leaves larger 

 than in either of the preceding (2'- 5') ; the involucre intermediate between them, 

 as to the form of the scales. Rays mostly short, pale bluish-purple or white. 



+- t- Heads middle-sized. (Involucre jfj - \' long.) 



21. A. simplex, Willd. Smooth or nearly so (3° -6° high), much 

 branched; the branches and scattered heads somewhat cmymbose at the summit; 

 leaves lanceolate, pointed, the lower serrate ; scales of the involucre linear awl shaped, 

 loosely and sparingly imbricated. — Shady moist banks, common. — Bays pale. 

 Approaches in its different forms the preceding and the two following. 



22. A. tcsauifdSBias, L. Nearly smooth ; stem much branched (2° -3° 

 high) ; the heads somewhat panicled or racemed ; leaves narrowly lanceolate, 

 tapering into a long slender point (2' -6' long), witli rough margins, the lower some- 

 what seirate in the middle ; scales of the hemispherical involucre linear-awl-shaped, 

 very slender-pointed, numerous, closely imbricated. — Low grounds, New York to 

 "Wisconsin, and southward. Rays short and narrow, pale purple or whitish. 



23. A. CslriaeilS, Nees. Smooth, or the branches rough or pubescent; 

 leaves lanceolate, somewhat pointed, or the upper short and partly clasping; 

 heads racemose along the ascending leafy branches ; scales of the obovate invo- 

 lucre lanceolate, abruptly acute, closely imbricated. — Moist soil; common. Leaven 

 firm in texture, smooth, or rough above. Rays rather large, bluish, purplish, 



