234 COMPOSITE, (composite fajiilt.) 



of tlie involucre imbricated inS-b rows, linear, with acute or awl-shaped spreading 

 or recurved green tips ; rays large and numerous, bright purplish-blue. — Moist 

 places, along streams, &c. : common eastward. — Plant l°-5° high, with large 

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

 varieties including A. thyrsiflorus, Hoffm., A. laxus, Willd. (a form with more 

 leafy involucres), A. prffialtus, Pair., A. elbdes, Torr. Sf Gr. . also A. salieifolius, 

 Scholler, the oldest name of all. 



28. A. punlceus, L- Stem tall and stout, rough-hairy all over or in lines, 

 usually purple below, panicled above ; leaves oblong-lanceolate, clasping by an auri- 

 cled base, sparingly serrate in the middle with appressed teeth, rough above, nearly 

 smooth underneath, pointed ; scales of the involucre nairowly linear, acute, loose, 

 equal, 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 rigid bristly hairs. 



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

 out ; growing in shade. 



29. A. prenanthoides, Muhl. Stem Zoa!i(l°-3° high), corymbose-pani- 

 cled, hairy above in lines ; leaves rough above, very sfs,ooth underneath, ovate-lanceolate, 

 sharply cut-toothed in the middle, conspicuously taper-pointed, and tapering below in a 

 long contracted entire portion, which is abruptly dilated into an auricled-heart-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 the branches or somewhat corymbed, showy : scales of the invo- 

 lucre very numerous, with loose and spreading or recurved mostly foliaceous tips, 

 usually more or less glandular or viscid, as are the branclitets, <f-c. 



H— Involucre imbricated, the scales in several or many ranks. 



30. A. grandifl6rUS, L. Bough with minute hispid hairs; stems slender, 

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

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

 squarrose many-ranked involucre; rays bright violet (1' long); achenia hairy. 

 — Dry open places, Virginia and southward. — Heads large and very showy. 



31. A. Oblongifdlius, Nutt. Minutely glandular-puberulent, much branched 

 above, rigid, paniculate-corymbose (l°-2° high) ; leaves narrowly oblong orlance- 

 olate, mucronate-pointed, partly clasping, thickish { 1 ' - 2' long by 2" - 5" wide) ; 

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

 achenia canescent. — Banks of rivers, from Pennsylvania (Huntingdon County, 

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

 middle-sized or smaller. 



32. A. ameth^Stinus, Nutt. Taller than the foregoing (2° -5° high), 

 more upright, with 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 spreading ; rays light clear blue. — Moist 

 grounds, Massachusetts (near Salem, Cambridge, &c., Nutlall, Dr. Bobbins, &c. : 

 Amherst {Prof. Tuckerman), Illinois {E. Ball), and Wisconsin. 



