318 RYDBERG: Rocky MOUNTAIN FLORA 
herbarium of the New York Botanical Garden there are several 
Scandinavian specimens of E. droebachensis Mueller (E. Muelleri 
Lund.), one from the vicinity of Christiania; the town of Droebach 
is only a short distance south of Christiania. These specimens 
are perfectly matched by specimens from Quebec, Subarctic Am- 
erica, Yukon, Canadian Rockies, and Colorado. Erigeron acris 
L., which is included in the New Manual, is on the contrary not 
found in America. It differs from all the North American species 
of the group, except the very rare E. alpinus, in having villous 
rather than hirsute or puberulent involucres. © 
ERIGERON COMMIXTUS Greene, Pittonia 5: 58. 1902 
E. cinereus A. Gray, Mem. Am. Acad. 4: 68.1849. Not E. cinereus 
H.& A. 1836. 
E. colo-mexicanus A. Nels.; Coult. & Nels. New Man. Cent. 
Rocky Mts. 529. 1909. 
Another specific name proposed by Professor Nelson, Erigeron 
colo-mexicanus, to replace the untenable E. cinereus A. Gray, is in 
my opinion rather distasteful. Fortunately I do not need to use 
the name, as the same species has been described by Dr. Greene 
under the name E. commixtus. 
ERIGERON UNIFLORUS L. Sp. Pl. 864. 1753 
The typical form of this species is, so far as I know, not found on 
this continent. As Dr. Greene has pointed out, the European 
species is characterized by narrow erect or ascending rays. This 
character is found also in Erigeron pulchellus unalaschkensis DC. 
Prod.5: 287 (E. uniflorus pulchellus Fries), which is not uncommon 
in America from Greenland to Labrador, Montana, and Alaska. 
In the latter the involucre is more or less turbinate, tapering into 
the enlarged end of the stem, and black-hairy, while in the typical 
E. uniflorus the involucres are hemispheric, and more or less white- 
hairy, and the stem is not thickened. Whether the two are specific- 
ally distinct or not is hard to tell. In Greenland both forms are 
found. If the variety is to be regarded as a species, Erigeron una- 
laschkensis (DC.) is the only available name, as E. pulchellus has 
been used by Michaux for another species. 
The plant referred to Erigeron uniflorus in the Flora of Colorado 
