A FLORA IN NORTHERN OREGON 317 



A SECTION OF TPPEK SONORAN FLORA IX NORTH- 

 ERN OREGON. 



MORTON E. PECK. 



From July -4 to July 16, 1915, the writer was stationed at 

 Umatilla. Oregon, as special field agent of the United States 

 Biological Survey. A part of the work assigned was the gather- 

 ing of data in regard to the general character of the vegetation 

 and the listing of the species identified. Most of the facts here 

 given were embodied in a somewhat briefer form in the official 

 report. 



Umatilla is a small town on the south bank of the Columbia 

 river, in Umatilla county. 110 miles from the eastern boundary 

 of the state, and 205 miles from the Pacific coast. The eleva- 

 tion above sea level is less than 200 feet, and is therefore cpiite 

 negligible as a climatic factor, while the Cascade mountains to 

 the westward cut off most of the moisture from the Pacific. 

 These conditions render the climate extremely dry and hot dur- 

 ing the summer; moreover in June. July and August strong 

 hot winds blow almost daily up the Columbia, greatly intensify- 

 ing the general aridity. The annual precipitation is about 8.70 

 inches. Except along the streams, the vegetation, as might be 

 expected, consists of only such plants as can endure rather se- 

 vere xerophytic conditions. 



The Umatilla river, a considerable stream, empties into the 

 Columbia near the town. Much of the water is now being tak- 

 en out by an extensive government irrigation project. Besides 

 tiie Columbia and Umatilla rivers, there is very little water in 

 the section studied except several small ponds to be mentioned 

 presently. 



Along the immediate shore of the Columbia there are in 

 places small muddy pools and bayous, hut for the most part the 

 ground a few yards back from the margin is quite dry. There 

 is also a little damp land along the Umatilla, which occasionally 

 expands into small swampy strip-. In many places along the 

 hanks of the latter stream there is abundant seepage. 



