234 coMPOsiTJE. (composite family.) 



of the inrolucrc ImhiicnUd in 3 - 5 roirs, linear, icith acute or atcI-sJiaprd spreading 

 or recurved green tips ; rays larj^c juul niunerous, bright purplisli-blue. — Moist 

 places, along streams, &c. : eoiinnoii eastward. — riant l°-5" high, with large 

 and showy heads ; very variable in the foliage, involucre, &c. ; its multiforia 

 varieties inchiding A. thyrsiHorus, Ilojfin., A. jaxus, Willd. (a form wiih more 

 leafy involucres), A. jinualtus, Poir., A. elodes, Tvrr. cj- Cr. : also A. salicifolius, 

 Scholler, the oldest name of all. 



28. A. punieeus, L. Stem tall and stout, rom/h-hiiiri/ all over or in lines, 

 Msually purple below, panicled above; leures olilong-lanccolate, claapiug lii/ an uuri- 

 cLd liiise, spuriuijlji serrate in tiie middle ivith nppress<d teeth, rough above, nearly 

 smooth luiderneath, pointed ; scales of the involucre narrowly linear, acute, loose, 

 egiuil, in about 2 rows; rays long and showy (lilac-blue, paler or whitish in 

 shade). — Low thickets and swamps, very common. — Stems 3° -6° high, in 

 open grounds rough with ri<;id bristly hairs. 



Van vimineus (A. vimineus, Willd.) is a variety nearly smooth through- 

 out; growing in shade. 



29. A. prenanthoides, Muhl. 5'^r?m /off (I°-.'}°high), corymbosc-paui- 

 cled, hairi) ahore in lin<s; leaves rough aliove, very snimlh undirnialli, ovalc-lunceolute, 

 sharply mt-tootlied in the middle, conspicuously taper-jminted, and tapering below in a 

 long contracted entire portion, which is abruptly ddated into an auricled-heurt-shaped 

 clasping base; scales of the involucre narrowly linear, with recurved-spreading 

 tips; rays light blue. — Borders of rich woods, W. New York to Wisconsin, and 

 southwards to Virginia. 



******* Leaves entire, those of the stem sessile, the base often clasping: heads 

 solitary terminating tlie branches or somewhat corymbed, showy: scales of the invo- 

 lucre very numerous, with loose and spreading or recurved mostly fuliaceous tij>s, 

 usually more or less glandular or viscid, as are the branchlets, ij-c. 



■*- Inrnlnrre imbricated, the scales in several or many ranks. 



30. A. grandiflbrus, L. Rough with minute hispid hairs ; stems slender, 

 loosely mucii branched (l°-3° high); leaves very small (i'-l' long), oblong- 

 linear, obtuse, rigid, the uppermost passing into scales of the hemispherical 

 squarrosc many-ranked involucre; rays bright violet (I' long); achcuia hairy. 

 — Dry open ]>laccs, Virginia and southward. — Heads large and very showy. 



31. A. oblongifblius, Nutt. Minutely glandular-puberutent, much branched 

 above, rigid, paniculate-corymbose (l°-2'' high) ; leaves narrowl y oblong or lancer 

 olate, mucronate-pointcd, partly clasping, thickish (l'-2' long by 2" -5" wide) ; 

 scales of the involucre broadly linear, appresscd at the base; rays violet-purple; 

 achcuia canescent. — Banks of rivers, from Penn.sylvania (Huntingdon County, 

 Prof. Porter !) and Virginia to Wisconsin, Kentucky, and westward. — Heads 

 miildlc-sizcd or smaller. 



32. A. amethystinus, Xutt. Taller than the foregoing (2° -.5° high), 

 more ui)right, witli more hirsute and not at all glandular or viscid pubescence ; 

 heads more racemose on the branches and smaller; involucre only about 3" in 

 diameter, the tips of the scales less s))reading ; rays light clear blue. — ^ Moist 

 grounds, Massachusetts (near Salem, Cambridge, &e., Nuttall, Dr. liobbins, &.c. : 

 Amherst (Prof. TucLcrman), Illinois (f. Hall), and Wisconsin. 



