Southeastern Washington and Adjacent Idaho. rf 
dwarfed bunches of Agropyron which is better developed on the 
talus slope below. This gives way in the deeper soils of the 
depressions or on protected slopes to various lupines, species of 
Poa, Balsamorhiza, Hieracium, Gaillardia,and other species. The 
depressions, if alkaline, may be clothed with dense growths of 
Distichlis spicata, Spartina gracilis, or Poa brachyglossa and these 
surrounded by a more or less distinct zone of Elymus condensatus. 
The vegetational differences often occur in areas so local as 
to be seen at a single glance. Alternating with a talus slope of 
lichen-covered basaltic blocks and only a few feet away, may be 
seen other slopes which at a little distance appear well clothed 
with herbaceous vegetation. Such are the interesting situations 
offered by the rocky soils of canyons and scab-lands. 
DESERT SCRUB FORMATION 
In the region under investigation the above formation is repre- 
sented only in the extreme western part. This formation oc- 
cupies much of the Columbia Basin, extending eastward to an 
altitude of about 1,200-1,300 feet, and on southerly slopes much 
higher. Excepting such species as are confined to the moist 
ground along perennial streams, the great majority of plants are 
either shrubs or thick-rooted perennial herbs or short-lived 
annuals. The most conspicuous and ecologically important plant 
is Artemisia tridentata. Other dominant species are the rabbit 
brush, Chrysothamnus nauseosus, C. viscidiflorus, the scab-land 
sage, Artemisia rigidia, the antelope brush, locally known as the 
black sage, Kunzia tridentata, and, in alkaline situations, the 
greasewood, Sarcobatus vermiculatus. 
The life conditions in this region are strikingly more severe 
than in the region of the high prairies eastward. During the 
summer of 1914, Mr. James G. Dickson; my one-time student, 
made determinations of water content, evaporating power of the 
air, and soil temperature for a period extending from July 5 to 
August 15, at Moxee, Washington, in the heart of this formation. 
He found that the average daily evaporation throughout the 
period from standard atmometers.was 51 c.c., while during several 
days in August it reached 74 c.c. The soil moisture at 6 and 12 
fa 
