COMPOSITE FAMILY. 237 



h- +- Scales variously imbricated, the tips .herbaceous (green) and spread- 

 ing, or the outer ones wholly leaf-like. 



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



A. sericeus, 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. 



•w- ++ Leaves not silvery-silky, various. 



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

 leaves all prominently cordate. 



II Bays about 40 ; involucral scales squarrose. 



A. an6malus, Engelm. Pubescent and roughish, 2°-4° ; upper leaves 

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

 W. and S. 



II || Bays 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. sagittifolius, 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. cordifdlius, 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. azureus, 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. Novv-Belgii and A. oblongifolius, 

 below, may be sought here.) 



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



A. Isevis, 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. Ndvce-Anglise, 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. 



