A FLORA IN NORTHERN OREGON 323 



Iii concluding this brief account of the distribution of the 

 flora in the neighborhood of Umatilla, it may be said that there 

 are few other sections of moderate elevation in the state where 

 the vegetation is so poor in species and so scant in quantity. 

 and that this poverty doubtless is due to the low annual precipi- 

 tation, high summer temperature, strong winds, and loose, light 

 character of the soil. Omitting the vegetation of the river 

 banks and cultivated ground, the flora is pronouncedly Upper 

 Sonoran. Perhaps no better example of the zone is to be found 

 in Oregon. 



The following is a complete list of the species identified, with 

 brief notes as to abundance, distribution, etc. 

 Typha latifolia L. Plentiful along the Umatilla. 

 Potamogeton lonchites Tuck. Rather common in the Umatilla 



and in irrigating ditches. 

 Potamogeton pusillus L. Extremely abundant' in the Umatilla 

 and in irrigating ditches. In the latter it grows in such 

 quantities as to completely choke them up, and must fre- 

 quently be cleaned out. 

 Alisma plant ago-aquatic a L. Common in mud along the Uma- 

 tilla. 

 Paspalum distichum L. Plentiful in places on the banks of the 

 Umatilla where there is abundant seepage. 



Panicum crus-galli L. Common in damp, especially cultivated 

 ground. 



Panicum barbipulvinatum Nash. Very common along irrigating 

 ditches. 



Oryzopsis hymenoides (R. and S.) Rick. This remarkable grass 

 is one of the most abundant of the family in this locality. 

 It grows in large, dense tufts that apparently persist for 

 many years. It is most plentifully distributed on the dry 

 sandy strip bordering the immediate banks of the Columbia, 

 but is also scattered over the high arid section. 



Phleum pratense L. Frequent in moist ground. 



Polypogon manspeliensis (L.) Desf. Very abundant in wet 

 places along the Umatilla. 



Sporobolus depauperatus (Torr.) Scrib. Common on gravellv 

 bars along the Columbia. A very depressed and dwarf 

 form. 



