COMPOS1TAE (THISTLE FAMILY) 



11 a Leaves usually rough above, not glaucous beneath 



BLUE WOOD ASTER. (A. cordifblius.) 

 b Leaves smooth, usually glaucous beneath 



LOWRIE'S ASTER. (A. lowrieanus.) 



12 a At least the lower leaves, and sometimes the stem leaves, 



narrowed or constricted below the middle and widened 



and clasping at the base 13 



b Leaves not completely as in a 15 



13 a Leaves toothed above the middle 



CROOKED-STEM ASTER. (A. prenanthotdes.) 

 b Leaves usually entire 14 



14 a Leaves ovate to oblong-lanceolate, ^-3 in. long, usually 



rough LATE PURPLE ASTER. (A. patens.) 



b Leaves lanceolate to oblong, 1-6 in. long, not usually 



rough THIN-LEAVED PURPLE ASTER. (A. phlogifblius.) 



15 a Stem leaves more or less clasping at the base 16 



b Stem leaves sessile or petioled, not clasping at the base 22 



16 a Bracts of involucre with glandular hairs 17 



b Bracts of involucre not with glandular hairs 19 



17 a Ray flowers 40-60; leaves lanceolate; branchlets with 



glandular hairs. NEW ENGLAND ASTER. (A. nbvae-dngliae.) 

 b Ray flowers 20-30; leaves ovate to oblong-lanceolate or 

 sometimes lanceolate; branchlets not with glandular 

 hairs 18 



1 8 a Leaves lanceolate to oblong 



THIN-LEAVED PURPLE ASTER. (A. phlogifblius.) 

 b Leaves ovate to oblong-lanceolate 



LATE PURPLE ASTER. (A. patens.) 



19 a Upper branches densely hairy 20 



b Upper branches not densely hairy 21 



20 a Leaves entire. .. .NEW ENGLAND ASTER. (A. nbvae-dngliae.) 

 b Leaves usually coarsely toothed and rough above 



PURPLE-STEM ASTER. (A. punicens.) 



21 a Stem usually glaucous; involucre bell-shaped, its bracts 



appressed SMOOTH ASTER. (A. laevis.) 



b Stem not glaucous; involucre hemispheric, its bracts 



spreading NEW YORK ASTER. (A. nbin-belgii.) 



22 a Leaves silvery-silky on both sides; heads in wand-like 



racemes SILVER ASTER. (A. concolor.) 



b Leaves not silvery-silky on both sides 23 



23 a Heads when open %-z in. broad 24 



b Heads when open Vi in. or less broad 31 



24 a Lower leaves oval to oblanceolate, petioled; branches 



and bracts of involucre usually with glandular hairs 



SHOWY PURPLE ASTER. (A. spectdbilis.) 

 b Lower leaves lanceolate to oblong; no glandular hairs 



present 25 



231 



