THE BOTANY OF THE ROUTE. 
13 
the country becoming very mountainous, and therefore well wooded. Southward it is continuous 
with the central plains of Oregon, through them with those of Utah, and through the South 
Pass with the vast plains extending eastward to the Mississippi river. 
In order to show the peculiarities in the vegetation of the plain region, I have included the 
plants collected there in a separate hst. Though made at an unfavorable season, and few in 
number, they show a marked dissimilarity from those obtained west of the mountains, yet many 
of the latter belonging to the prairies west of the mountains are also known to be found on the 
plains of the central districts. 
One peculiar group of shrubs represent in this region the forest trees, and are characteristic 
of all the plain regions between the eastern base of the Rocky mountains and the Pacific. 
(Purshia tridentata, Artemisia tridentata, Linosyris albicanlis, L. viscidijlora^ Sarcobatus ver- 
micularis. ) 
As the most characteristic animals, I refer to the badger, coyote, or barking wolf, cock of the 
plains, or sage fowl; sharp-tailed grouse, or prairie chicken, and other smaller kinds, mentioned 
more particularly elsewhere. The antelope, buffalo, prairie dog, and some others found in other 
parts of the plains, doubtless are sometimes to be met with in this Territory, though we neither 
saw them nor heard of them as being common. 
The various divisions of the plains due to differences of elevations, soil, and moisture, have 
each their peculiarities, which would require a long description, had my opportunities been 
sufficient to make it complete. A short notice of the most striking may not be without interest 
here. 
The high ridges forming spurs of the Cascade range, extending with a gradual slope from 
the pine forests down to the Columbia on each side the Yakima valley, between its branches, are 
too dry to serve as anything but a grazing region. Some portions near their summits are also very 
rocky and barren, but these are comparativyly small. The greatest obstacle to cultivation is 
the absence of means of irrigation, but there can be little doubt of the success of winter grains 
on many parts of these ridges. The Spokane plain, between that river and the Snake, west of 
longitude 118°, resembles, in soil and elevation, the lowest part of these ridges, being from 500 to 
2,500 feet in elevation. But being a great plateau, it has the advantage of retaining moisture, 
and in many parts are tracts sufficiently irrigated naturally for general cultivation. Alkaline 
lakes and marshes, and some very rocky portions, are all that cannot be made use of, but these 
seem to occupy comparatively a small extent of it. 
On all the branches of the northern Columbia crossed by us we found valleys of various 
extent, which form the best portion of the plain region. Terraces varying in height from five 
to two hundred feet above the water border these valleys, and present various soils, from the 
very dry gravel of the ridges down to the fertile alluvium of the river banks. The change in 
the native vegetation from one to another of these is very remarkable, indicating an adaptation 
for various crops. Long rank grass covers the moister portions of the bottoms, and there is 
always some timber close to the water, except towards the mouth of the Yakima. Those valleys 
north of latitude 48° are doubtless the best in soil and climate., crops doing admirably at Fort 
Colville without any irrigation. 
The lands immediately along the Columbia itself, from just below the mouth of the 
Spokane to near the Dalles, and all the adjoining region betow the elevation of about 2, 000 
feet, seem available only for grazing without the assistance of irrigation. But it has, as well 
as the higher valleys, great advantages for effecting this object in the terraces which often 
