522 BOTANICAL INFORMATION. 



the former, grow Artemisia tridentata, the common frutescent 

 Chrysocoma and Rumex venosus ; the latter, as on the sands 

 of Platte-river Valley, binds the sand with its long roots and 

 those of a straggling sufFrutescent Psoralea (P. verrucosa^ 

 Nutt.) A species of Allionia (651), as on the Platte, occmi 

 also here, but prostrate, with Cleome aurea, from I to 4 feet 

 high ; Ambrosia acanthocarpa ; and, above all abundant, the 

 annoying Opuntia fragilis. The muddy willow- groves, near 

 the mouth of the Walla-Walla river, exhibit vestiges of Xan- 

 thium macrocarpon, with Polygonum Persicaria, invested by a 

 Cuscuta, 674, probably Cuscuta polygonorum, (Englm.) ; and 

 on the desert basaltic plain above, I found the Mamittaria, 

 mentioned in the remark to a former chapter. 



I cannot attempt a description of the vegetation of Lower 

 Oregon, owing to my rapid passage from Fort Walla- Walla 

 to Fort Vancouver. The desert plains cease at the foot of 

 the Cascade Mountains, a Blue Mountain spur separating 

 Upper and Lower Oregon. Here the Cupuliferm make their 

 first appearance since we left the south fork of Platte river. 

 The country, enclosing the Columbia torrent, is in parts a 

 desolate wilderness, inhospitable even to the savage, whom I 

 nowhere found more docile, and leading a more wretched life. 

 Below this difficult mountain barrier, and about 140 miles 

 from its mouth, the Columbia becomes suddenly placid, much 

 resembling the Mississippi, only wanting the luxuriant forests 

 of deciduous trees, which are rather mossy and poor. The 

 pines, however, with which the country is over-stocked, are 

 of great size, 120 feet being about the average height ; some of 

 them measuring 220 feet, and more, with a proportionate 

 diameter of trunk. 



Many interesting trees and shrubs I noticed on my rapid 

 passage, but constant rain forbade the possibility of collecting 

 specimens, and the reader must remain satisfied with the in- 

 formation which Mr. Douglas has given. 



I arrived safely at Fort Vancouver with the Brigade of the 

 Hon. Hudson's Bay Company, commanded by one of their 



