64 Wyoming Expei'tnient Station. 



ually comes to form a larger proportion of the whole until 

 at 9,000 feet and upward it constitutes practically an 

 unbroken forest to the exclusion of other species. At 

 timber line it becomes scattering, dwarfed and depressed, 

 spreading out like a huge mat under the enormous pres- 

 sure of the winter snows. 



Practically the same conditions prevail in the Wind 

 River Mountains, and probably, though I cannot speak 

 from observation, in the Big Horn Mountains. 



Of the fruticose and herbaceous vegetation I need 

 not speak here, although the summits of these ranges 

 yield many beautiful and strictly alpine forms. These 

 all receive comment in their proper place in the list, so 

 space may not be consumed for that purpose here. 



T^E TREES OF THE STATE. 



A list of the trees of the state is indeed very short 

 and were those on the border line between trees and 

 shrubs excluded in would be shorter yet by a third. 



Rocky Mountain Yellow Pine {Phiiis ponderosa scopuloruvi). 



Rocky Mountain White Pine {Plniis Jiexilis). 



Lodge Pole Pine {Pintts Murray atia). 



Engelmann's Spruce [Picea Engelmatini). 



Blue Spruce {Pkca pungeiis). 



Douglas Spruce {^Pseiidotsuga Douglasii). 



VwgmiA ]\in\\)tv [Juniperics Virginiana). 



Black Cottonwood {Popu/iis ajigustifolia). 



Rydberg's Cottonwood {Populus acuminata). 



Quaking Asp. Aspen {Popiilics tremuloidts). 



Willow (ySalix lojt^ifo/ia). 



Willow {Salix flavescens). 



Willow {Salix amygdaloides). 



Willow (^Salix lasiandra). 



Green Ash {Fraxiniis viridis). 

 ' Box Elder {Negundo aceroides). 



