198 Rhodora | [NOVEMBER 
more generally distributed than its representation in the herbaria 
would iridicate. Careful study of the material and comparison of the 
original description leads to the somewhat surprising conclusion that 
it is exactly the plant described by Muhlenberg as B?dens connata, 
while the commoner plant with simple slender-petioled leaves which 
is passing as В. connata is ordinarily so distinct as to merit varietal 
recognition and was even characterized as a species, В. petiolata, by 
Nuttall. 
As treated by recent authors Bidens connata is supposed to be the 
plant (Nuttall’s B. petiolaia) with usually simple distinctly petioled 
leaves, while the occurrence of 3-lobed leaves if noted at all 1s con- 
sidered unusual. ‘This is a somewhat natural conclusion, since the 
herbarium representation of the former is so much more complete 
than of the latter plant. ‘The two plants in their extreme forms are 
very different, but the writer has sought in vain for constant characters 
by which they can be clearly separated. 
The surfaces of the achenes at first seemed to offer good concomitant 
characters; for in some plants with the slender-petioled unlobed leaves 
the achenes are quite smooth, while in some specimens with the broad- 
petioled lobed leaves they are tuberculate or warty. ‘This presence 
or absence of warts on the achene has been much emphasized by 
European students of the group who, finding about various lakes of 
continental Europe B. connata with warty achenes, maintain that 
American specimens with smooth achenes cannot belong to the same 
1'*8. BIDENS connata. 
B. floribus discoideis, calyce exteriore flore triplo longiore, foliis caulinis ternatis folio- 
lis lateralibus connatis, floralibus oblongo-lanceolatis. W. 
Bidens connata. Muhlenberg. 
Verwachsener Zweyzahn. W. 
Habitat in America boreali. © (v. s.) 
Caulis laevis ramosus. Folia caulina petiolata ternata, foliolis lateralibus oblongis 
acutis serratis sessilibus, basi inferiore in petiolum decurrentibus, foliolum intermedium 
petiolatum oblongum utrinque attenuatum serratum. Folia floralia et summa ramea petio- 
lata oblonga utrinque attenuata serrata, Calyx duplex, exterior pentaphyllus, foliolis 
lanceolatis flore triplo longioribus; interior foliolis coloratis obtusis margine membranaceis 
aequalibus. Corolla discoidea. Differt a В. frondosa foliorum forma, calyce exteriore 
breviore tantum pentaphyllo. №.” — Willd. Sp. iii. 1718 (1804). 
2' 57, BIDENS *petiolata. _Glabra, foliis simplicibus petiolatis angusto-lanceolatis 
utrinque acuminatis serratis, floribus disc oideis, calyce exteriore mediocri. 
(Low, but considerably branched. The leaves all entire, attenuated below into a 
longish petiole, the smaller branch leaves often nearly entire. The outer calyx small. 
The flowers without rays and rather small. 
Hab. Оп һе margins of ponds in various parts of New England.” 
Nuttall, Jour. Acad. Nat. Sci. Phila., vii. pt. 1, 99 (1834). 
