INTRODUCTION. 341 
the genus Aster, being so much better known and (slightly modified) 
so much more universally distributed than the little-known local 
genus Cassinia, is much better suited for a so-called ordinal 
type. 
Of all the modern contributions to the study of Composite 
none are more important for the accuracy of observation and the 
due appreciation of characters and affinities than those of Asa 
Gray. His views (first exemplified in the 2nd volume of the 
‘Flora of North America,’ further carried out in a long series of 
memoirs or detached papers on the Composite of various collec- 
tions published in the * Smithsonian Contributions,’ in the reports 
of various American exploring or surveying expeditions, in the 
Proceedings of the American Academy, of the Boston Society, 
in Hooker's Journals of Botany, and other periodicals) may always 
be implicitly followed without any danger of being led into error, 
although sometimes a difference of opinion may exist upon such 
minor points as the generic or subgenerie value to be given to a 
group. The only real difficulty in his case arises from the dis- 
persion of his papers in such a large number of publications, not 
always within reach of the generality of botanists, and some of 
which it is scarcely possible not to overlook. 
There are many others whom I might mention as having con- 
tributed more or less beneficially or prejudicially to our know- 
ledge of Composite; but that would require the enumeration of 
the greater number of modern systematic botanists. Composite 
are so easy to examine, that botanists of very little experience 
are readily led into the belief that they have mastered every thing 
relating to a specimen they are examining; and if they discover 
some point not quite agreeing with the technical characters of the 
genus it is presumed to belong to, they are at once ready to 
establish a new one ; and there are few orders which have been so 
universally dabbled with, or where there have been so many 
repetitions of species, of genera, or of observations. The litera- 
ture of Hieracium and of Aster, for instance, is almost, if not 
quite, as bulky as that of Rubus and of Rosa; and generally the 
synonyms of this part of our‘ Genera Plantarum’ are nearly twice 
as numerous as the adopted generic names. 
There are, however, among the numerous more speculative 
naturalists whom the promulgation of the Darwinian theories 
have called into action, two who require notice as having specially 
taken up the subject of Composite with reference to those pro- 
