308 BOTANICAL GAZETTE [APRIL 
“achaeniis . . . apice setuloso-ciliatis calvis vel aristulis 1 vel 
2 brevissimis erecto—vel patenti—vel etiam recurvo—uncinulatis 
, Onustis saepe vero nudis . . . ; indeed, the plant might almost as 
well be considered a Bidens, but the habit is that of Coreopsis”). 
In referring the latter species to Coreopsis, he relied mainly upon 
its habital similarity to other (so-called) species of Coreopsis 
from Africa. But, as will be seen presently, some of these species 
belong in reality to Bidens. Therefore, this habital similarity, 
affording formerly an apparently good reason for the name Core- 
opsis Taylori, can no longer be given much consideration. 
The present writer, in bringing together the numerous species 
of Bidens for monographic treatment, has come to adopt fully the 
generic limits of these two genera as followed by recent American 
botanists. In brief, the genus Coreopsis is maintained primarily 
because of the peculiar habit and winged achenes of the Linnaean 
type species (excluding C. alba, C. Bidens, and C. alternifolia, Sp. 
Plant ed. 1. pp. 907-909. 1753; cf. Brrrron, Bull. Torr. Bot. Club 
20: 280. 1893). Similarly, the genus Bidens is maintained pri- 
marily because of the peculiar habit, strongly barbed awns, and 
wingless achenes of several of the Linnaean type species of Bidens. 
Among the species of either small group a fair degree of uniformity 
in several characters occurs. But on extending our observations 
to other species of Coreopsis and Bidens, we find remaining no 
absolute uniformity in even one distinctive character. However, 
one such character does persist to a surprising extent. It is the 
presence (in Coreopsis) or absence (in Bidens) of two lateral wings 
upon the mature achene. Among so many species from widely 
remote regions does this character separate two genera with differ- 
ent aspects that, im cases where other criteria are absent, it appears 
to offer the only logical basis of distinction. Accordingly, and 
with a view to thus delimiting these two genera more accurately, 
notably among the African species (where the generic limits tend 
to overlap) this basis of distinction is here adopted. As a conse- 
quence, it is found necessary to make the following transfers for 
the flora of Africa. This list includes only those species upon the 
types or other positively authentic material of which I have per 
sonally examined the mature achenes. 
