ee ee eS ee SL” Oe, 
TS. Pe 
24 Muhlenbergia, Volume 3 
The entire range of hills on the eastern side of the valley, 
with the exception of the highest peaks, the writer is inclined 
to include in the Upper Sonoran area of the Upper Austral zone. 
The common sagebrush is abundant throughout this area in a 
stunted form. Other common species are: 
Atriplex confertifolia Juniperus Californica Utahensis 
Atriplex canescens Pinus monophylla 
Atriplex Nuttallii Ramona incana 
Tetradymia canescens Sphaerostigma tortuosa 
Tetradymia spinescens Stipa comata 
Tetradymia glabrata Tricardia Watsoni 
In the lowest, usually alkaline, localities of the same area 
we find: 
Sarcobatus vermiculatus Salicornia herbacea 
Distichlis spicata Juncus balticus 
Spartina gracilis Triglochin maritima 
Lepargyraea argentea 
TRANSITION ZONE 
It is very evident that the plants of this region, occurring 
within the limits of this zone, must belong to the Arid Transi- 
tion area as indicated by Merriam in his scheme of classification. 
There are two distinct belts represented, and we are inclined to 
follow Piper and Hall and divide the area into an Upper and a 
Lower Transition area. ‘The Upper Transition area is to be 
represented by the yellow pine (Pimus ponderosa), and the 
Lower ‘Transition area by the common sagebrush (Artemisia 
tridentata). It is interesting to note that Piper in his Flora of 
Washington regards Artemisia tridentata as more characteristic 
of the Upper Sonoran area, and includes also several other 
shrubs which we regard as in the Transition area. There is 
little doubt but that owing to the ability of the sagebrush to 
adapt itself to exceedingly variable conditions both of altitude, 
moisture and soil, that it overlaps both areas so as to be almost 
inseparable. My observations lead me to believe, however, that 
