BOTANICAL INFORMATION. 521 



of drainage, for it is excessively hot in these valleys, their 

 almost perpendicular basaltic c6tes averaging 1,500 feet in 

 height. Thickets of Celtis and Crataegus are also filled with 

 Rhus, Ribes, Spiraea, and Rose bushes. The same is the case 

 in the sterile valley of Lewis River, the ground densely covered 

 with Euphorbia, Erodium, or Thlaspi (655), and the discoid 

 Cotula. Lower down appear again the scarlet Sida (S. obliqua, 

 Nutt.), joining the sub-fertile region and sandy desert, as in 

 Missouri territory. Crossing the cdte westward, we pass 

 over a region of prairies, deeply furrowed with ravines. On this 

 tract I observed sundry species of Espeletia, which I had not 

 seen before; none, however, either in flower or fruit; their 

 vegetation was over, but I could distinctly trace the form of 

 their leaves.* At considerable distances I met with a few 

 scattered plants of Bartonia lavicaulis, in full splendour. 

 Soon we reach the valley of Upper Walla-Walla river, the 

 territory of the haughty Cay uses, the handsomest Indians in 

 Upper Oregon, nearly related to the Saptonas, whose lan- 

 guage they have adopted, and with whom they make com- 

 mon cause in any undertaking. Following the Walla-Walla 

 river, we soon arrive at Wa'ialitpu, the seat of the tribe, with 

 an American Mission Station, a delightful tract, surrounded 

 by the saline sandy desert, the main Blue Mountain ridge 

 visible at the distance. This saline desert vegetation corres- 

 ponds nearly with that on the east-side, but the soda is here 

 not so copious. Fremontia vermicularis prevails again, higher 

 and more robust, but decidedly the same shrub. Of other 

 saline shrubs I found only Iva axillaris, with the annual 

 dtriplex argentea. But there grew abundantly with Fremontia 

 the Purshia tridentata, which is very large towards the Colum- 

 bia river, where the drift-sand lies very deep. Here, with 



* The leaves of the different species of Espeletia seem to take the form 

 of 8ome other Composites. Those of E. helianth. resemble Doronicum ; 

 those of E. 395, Silph. terebinthaceum ; of 419, Scolymus ; of the above, 

 Laciusa virosa and others. 



VOL. V. Q Q 



