413] FLORA OF BOULDER, COLORADO 265 



APPENDIX A. 



Tidestrom in the Am. Midi. Nat. 2, 35, tias descrited as a new 

 species this aspen under the name of P. aurea Tidestrom, with 

 the remarlt that it forms forests throughout Colorado, Utah, and 

 adjoining territory. But the differences relied upon to separate it 

 from Michaux's species seem to me to he at most varietal, and 

 hence I prefer to call the Colorado tree P. tremuloides aurea (Tide- 

 strom) Daniels. See page 98. 



