INTRODUCTION 
The genus Aster has been long admired for its beauty and di- 
versity. No lover of quiet natural beauty but feels its lingering 
charm. Few plants bear their wealth of bloom with a more un- 
conscious grace. No wonder that the all-expressing Greek should 
call the plant ‘the many-eyed.” Its ministry is not alone to the 
outer but to the inner sense, mee one say with Emerson 
Every aster in my h 
Goes home laden are a thought. 
The suggestions inspired by the variability of asters hinge a 
profound significance. The very quality which makes the genus so 
vexatious to the searcher after quick and certain definitions of 
species, makes it full of keenest interest to the student of variation. 
Variation—which is Nature—reaches a maximum development 
in Aster. This is true in two ways, for few species vary so insen- 
sibly into each other while in their unchanged native state; and 
few species are so rapidly modified under changed environment. 
It was with these feelings that my studies of Aster were begun 
about 1886, and with the hope that continued observation in the 
field might bring a glimpse of nature in the very act of the varia- 
tion process, I have sought to determine the respective varia- 
bility of characters and to indicate what effects have been produced 
by environment. It is sometimes suggested that in Aster new 
species are being formed by development from the old with more 
rapidity than in most genera of the present. If there is even the 
possibility that this is actually the case, it follows that there is 
needed more than usual care and exactness in the limitation of 
Aster-forms as at present known, to aid comparative work in the 
future. That the genus should present extreme difficulties of 
classification is the natural result from its plasticity. Toward 
Memoirs Torrey Botanical Club, Volume X. 
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