1906} SHANTZ—VEGETATION OF THE MESA 185 
the ‘“‘pine.”” The first has as facies Pinus edulis Engelm. and 
Juniperus monosperma (Engelm.) Sarg.; and. as principal species, 
Stipa Scribneri Vasey. The second has as facies Pinus scopulorum 
(Engelm.) Lem. and P. flex:lis James.; and as principal species, 
Arctostaphylos Uva-ursi (L.) Spreng. 
Fic. 11.—Pinus scopulorum invading the Bouteloua formation. 
In the zone at the base of the mountains lies the foothill woodland 
formation, while just above is the pine formation. Each of these 
‘ormations is invading the Bouteloua formation, and the one which 
lies higher on the mountains, the pine formation, is the more successful. 
A consocies of this formation dominated by Pinus scopulorum has 
pushed its way eastward far into Nebraska’ and carries with it many 
Of the principal and secondary species. P. flexilis drops out before 
the foothills are reached. Near Eastonville, Colo., this formation 
* Pound and Crements, Phytogeegraphy of Nebraska, 2d ed., Lincoln, Neb., 
1900, p. 336. 
