252 PITTONIA. 
makes the first mention of “ B. cernua” as inhabiting North 
America as well as Europe. His account of the species in 
general concludes with the note that it is native to Europe 
and North America. Then in a subsequent note, namely, 
under the exclusively American species, 5. chrysanthemoides, 
he says: “ Bidens cernua, with its varieties, I also have from 
North America.” Pursh a few years later confirms B. 
cernua as common in our country; and since then all our 
authors have accepted it. Before proceeding to discuss the 
question of our having B. cernua in America, I wish to call 
attention to certain marked peculiarities of this particular 
type of Bidens. 
Habitally these species diverge from the most genuine 
Bidens in that they are lower in stature, stouter and inclined 
to be succulent, as well as very leafy with undivided often 
connate leaves. Their ray-flowers when present are twice 
as numerous as in the typical group; and their achenes are 
often four-angled and four-awned, as well as of a much more 
strictly cuneiform outline, being widest, and even very em- 
phatically so, just at the summit, thence tapering to the 
base. Such characters of flower and fruit would warrant 
the recognition of a genus if the habital peculiarity of the 
group were as constant. But almost the same habit recurs 
in B. connata and its allies, which are of proper and genuine | 
Bidens as to their achenes. In view of these so nearly 
perfect connecting links between the two groups, I should 
not venture to propose B. cernua as the type of a genus. 
5. American Analogues of BIDENS ckRNUA, Linn. 
After careful and repeated comparisons made between 
European and American specimens of so-called B. cernua, I 
acknowledge inability to detect any strong technical char- 
acters upon which to separate them. Nevertheless they are 
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