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. PI. 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 



