COMPOSITAE (THISTLE FAMILY) 



25 a Upper stem leaves entire, the lowest sometimes toothed 26 

 b Stem leaves more or less toothed 27 



26 a Lower leaves oblanceolate, sometimes toothed; plant 



not growing on salt marshes. . BUSHY ASTER. (A. dumbsus.) 

 b Lower leaves linear to linear-lanceolate, entire; plant 

 growing on salt marshes 



PERENNIAL SALT-MARSH ASTER. (A. tenuifolius.) 



27 a Heads when open 1-2 in. broad, not in panicles 28 



b Heads i in. or less broad when open, in loose panicles 



or racemose-panicles 29 



28 a Leaves 1-2 in. long; heads few or solitary on slender 



stalks BOG ASTER. (A. nemoralis.) 



b Leaves 2-6 in. long; heads several in a corymb 



MOUNTAIN ASTER. (A. acuminatus.) 



29 a Heads numerous in leafy racemes on the branches; ray 



flowers white TRADESCANT'S ASTER. (A. tradescdnti.) 



b Heads in a loose panicle ; ray flowers violet, purplish, 



or white 30 



30 a Ray flowers usually white; leaves smooth 



PANICLED ASTER. (A. paniculatus.) 

 b Ray flowers not usually white; leaves often rough above 



WILLOW ASTER. (A. salicifblius.) 



31 a Heads in loose panicles, or terminal on the branches, 



not in i-sided racemes 32 



b Heads in more or less i-sided racemes, often recurved, 



on the branches 38 



32 a Stem densely hairy, not merely hairy in lines 



HAIRY-STEMMED ASTER. (A. hirsuticaulis.) 

 b Stem not densely hairy, sometimes hairy in lines 33 



33 a Lower leaves toothed 34 



b All leaves entire 35 



34 a Bracts of the involucre lanceolate; basal leaves narrowed 



into winged petioles. WHITE HEATH ASTER. (A, ericoldes.) 

 b Bracts of involucre linear; basal leaves not petioled 



BUSHY ASTER. (A. dumbsus.) 



35 a Plants growing in salt marshes 36 



b Plants not growing in salt marshes 37 



36 a Heads %-i in. broad when open; bracts of involucre 



lanceolate. PERENNIAL SALT-MARSH ASTER. (A. tenuifolius.) 

 b Heads %-'% in. broad; bracts of involucre linear 



ANNUAL SALT-MARSH ASTER. (A. subulatus.) 



37 a Bracts of involucre lanceolate; basal leaves narrowed 



into winged petioles. WHITE HEATH ASTER' (A. ericoides.) 

 b Bracts of involucre linear; basal leaves not petioled 



BUSHY ASTER. (A. dumbsus.) 



38 a Stems conspicuously rough or hairy throughout 39 



b Stems not rough or hairy throughout, often hairy in lines 41 



232 



