COMPOSITE FAMILY. 237 



t- >- Scales variously imbricated, the tips herbaceous (green') and spread- 

 ing, or the. outer ones wholly leaf-like. 



w- Leaves silvery-silky both sides, and sessile and entire. 

 A. serlceua, Vent. Slender, l-2 ; leaves lanceolate or oblong, 

 spreading ; involucre globular with spreading scales ; heads mostly soli- 

 tary, showy, violet. Dry soil, Wis., W. and S. 



A. cdncolor, Linn. Leaves crowded and appressed, as are the scales 

 of the obovoid involucre ; heads in a compound wand-like raceme, violet. 

 Near the coast, R. I., S. 



f* Leaves not silvery-silky, various. 



= Stem leaves all (or at least the lowest} cordate and petioled ; radical 

 leaves all prominently cordate. 



|| Bays about 40 ; involucral scales squarrose. 



A. andmalus, Engelm. Pubescent- and roughish, 2-4 ; upper leaves 

 small and nearly or quite sessile ; heads rather large, bright violet. El., 

 W. and S. 



|| || Hays 10-20, light-blue or white ; scales not squarrose. 



o All or part of the petioles wing-margined. 



A. undulatus, Linn. Leaves ovate or lance-ovate, the margins wavy 

 or slightly toothed, roughish above and downy beneath, the uppermost 

 with clasping petioles. Common. 



A. sagittifdlius, Willd. Rigid and erect, 2-3, with ascending 

 branches ; leaves ovate-lanceolate, the lower cordate and on margined 

 petioles, the upper becoming narrower ; involucre oblong, the scales 

 narrow-tapering and loose. Common, N. and S. 



o o Petioles not wing-margined (except occasionally in the first). 



A. cordif61ius, Linn. Stem much branched, the branches diverging 

 and bearing very numerous panicled heads ; lower stem leaves all pro- 

 minently heart-shaped, the petioles ciliate and only slightly or not at all 

 margined ; involucre obconical, with short and nearly obtuse, appressed 

 tips. Common, Can. to Ga., and W. Variable. 



A. aztireus, Lindl. Heads larger ; leaves ovate-lanceolate or oblong, 

 rough, the petioles usually long and hairy, the uppermost becoming 

 nearly linear and sessile, or on the branches even awl-like ; involucre 

 obconical, slightly pubescent. N. Y., S. and W. 



= = Stem leaves clasping or sessile (or if short-stalked, not cordate), 

 various. 



o Leaves broadish, prominently cordate-clasping or with a winged- 

 petiole-like base. (Forms of A. Novi-Belgii and A. oblongifolius, 

 below, may be sought here.) 



x Leaves entire (rarely very obscurely toothed in first two). 

 A. laevis, Linn. Smooth and glabrous, often glaucous, 2-4 ; leaves 

 thickish, lanceolate or broader, the upper auriculate, or cordate, clasp- 

 ing ; involucre hemispherical, with abrupt green tips ; rays blue. Com- 

 mon and handsome. 



A. patens, Ait. Rough-pubescent, l-3, the branches loose and 

 widely spreading ; leaves ovate-oblong or longer, rough above and on the 

 margins ; involucre ovoid, scales with pointed spreading tips ; rays purple. 

 N. and S. 



A. N6vae-Anglie, Linn. Tall and stout, 3-8, hairy, very leafy ; 

 leaves lanceolate and acute, pubescent ; scales nearly equal and loose, 

 awl-like, glandular-viscid ; flowers large, rose or purple. Can. to S. C., 

 and W. ; also cult. 



