v BIOTIAN ASTERS 
indeterminate forms, most of which represent not casual specimens 
but forms which I have followed up year after year. 
Iy plan of treatment, practicable only in an extended mono- 
graph li e the present, is to present not only a full description of 
each species, but also all that is known of its history and of its 
conditions of.variation. The full descriptions given being neces- 
sarily long, I preface to each of these a brief diagnosis, distin- 
guished by lines differently spaced, and serving to condense into 
few words some salient features which are instantly obvious and 
distinctive of the species. 
A similar but still briefer characterization of each species will 
be found in the analytic key, pp. 89-99. The difference in the 
case of the key-character is that it is so drawn as to emphasize 
comparative features rather than the absolute ; with principal refer- 
ence to distinctions between closely allied species. A yet briefer 
single-line key with page references, for use as a first or trial clue, 
will be found at the end of the volume, next preceding the general 
index. : 
Where a species has been described before, in order to present 
its history fairly, I introduce the exact words of its original 
description as an integral part of its history; and to supplement 
this, I quote from subsequent descriptions such additional or 
altered characters as make any real contribution to the original 
description. I have been at much pains to follow out this treat- 
ment, from the feeling that a monograph should not be merely a 
series of references to scattered literature, but should instead bring 
together into one convenient series, the substance of all previous 
work on the subject. 
Types of specimens of all the new species here described are 
to be found in my own herbarium ; with a few exceptions, stated 
under the respective species. Their locality is given with each 
species. The locality-list following each description consists, 
unless otherwise designated, of flowering specimens which I have 
collected at the date and place given, and usually still retained in 
my herbarium. In cases not of my own collecting, the name of 
the collector and the herbarium is added. 
I desire again to acknowledge the many courtesies received 
from other botanists,* and especially the continued kindnesses ex- 
* See Mem. Torrey Club, ro: 3, 4. 
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