STUDIES IN THE COMPOSITA. 247 
least two very distinct species. The most important seg- 
regate from it was proposed by myself in July, 1899, under 
the name of B. vulgata; while a few weeks later, Mr. 
Wiegand of Cornell University, having attempted the same 
segregation, gave out a good description of the true B. 
frondosa under the new name of B. melanocarpa, at the same 
time characterizing as B. frondosa what is almost if not pre- 
cisely my new B. vulgata. The writer says: '“ Considerable 
difficulty has been experienced in deciding whether Lin- 
neus’ plant was of this species or the preceding.” And 
when Linnzeus’ account of the plant is referred to as being 
“the original description" we appreciate the difficulty ; 
and from that initial point we judge it to be altogether in- 
superable. From that brief diagnosis which Linnæus con- 
structed, there would be no deciding which of several species 
he had in view; and so we may be glad that it is not “the 
original description.” But the earlier descriptions, to which 
his bibliography of the species gives a clew, may help us to 
a conclusion. Let us examine some of them. And the 
examination may illustrate some of the difficulties, not, 
however, insuperable, incident to a full interpretation of 
Linnæus and pre-Linnzan authors. 
From that earliest appellation, * Eupatorium Canadense, 
flore luteo" of the Hortus Regius Parisiensis not much light 
seems likely, at first thought, to be gained as to what 
Bidens frondosa ought to be. It carries us back to the 
time when the three or four species of the genus known 
were all considered as Eupatoriums; allies of E. cannabinum. 
Why was this one designated as yellow-flowered ? It was 
always placed next to B. tripartita, as nearly related to that; 
yet B. tripartita, though its minute disk-corollas are yel- 
lowish, was never, either as Eupatorium or as Bidens, 
1 Bull. Torr. Club, xxvi, 409. 
