2 BULLETIN 545, U. S. DEPARTMENT OF AGRICULTURE. 
of tannic acid, which renders them unpalatable are of little or no 
value for forage. 1 
In order to gain an intimate knowledge of the habits, requirements, 
and life history of the more important species, a stud}?- was initiated 
in 1907 by the Forest Service, in cooperation with the Bureau of 
Plant Industry, upon the Wallowa National Forest in northeastern 
Oregon. Data on the relative palatability of the different forage 
plants were gathered by following bands of sheep and observing 
their choice of feed as they grazed. Afterwards the relative value 
of the individual range plants was determined by studying (1) their 
abundance, distribution, time of flower-stalk production, aggressive- 
ness, reproduction (both vegetatively and by seed), and seed habits; 
and (2) their palatability and nutritiousness at various times during 
the grazing season and their ability to withstand trampling. The 
plan of study and the methods used are fully described at the end of 
the bulletin. 
While the results of the study are largely based upon observations 
in the high mountains in Oregon between elevations of 5,500 and 
8,000 feet, they should nevertheless be helpful to stockmen through- 
out the West in revegetating the range, since many of the species 
described are widely distributed, and the genera represented are 
among those of first importance on most of the natural range lands of 
the West. 
A photograph of each important species in natural size accom- 
panies its description, but where the general characters of two or 
more species of the same genus are similar, a single photograph is 
used. With the exception of Plate XXXVIII all specimens selected 
for photographic purposes were either in flower or fruit, or both, 
and care was taken to show the general character of the root sys- 
tem, habit of growth, and external structure. Not only will these 
photographs make possible, in practically every instance, the recog- 
nition of the same species when met with in the field, but also other 
species of the same genus will be recognized as congeneric, although 
the specific name may not be known to the observer. 
CHARACTER OF THE RANGE AND FORAGE STUDIED. 
Between the lower and higher grazing lands of the mountains of 
northeastern Oregon is a difference in elevation of about 7,000 feet. 
Along with this wide altitudinal variation go widely different growth 
conditions. Thus, according to the character of the vegetation, 
the lands studied may be classified into four zones. 2 
1 The results of natural revegetation studies based upon observation of the plants described in this bulle- 
tin are presented by the writer in U. S. Dept. Agr. Bui. 34, " Range Improvement by Deferred and Rotation 
Grazing," 1913, and in the Journal of Agricultural Research, Vol. Ill, No. 2, "Natural ReveszeUUion of 
Range Lands Based upon Growth Requirements and Life History of the Vegetation,'' 1914. 
- Mcrriam, C. Hart, "Life Zones and Crop Zones of the United States," U. S. Dept. of Agriculture, 
Biological Survey Bui. No. 10, 1898. 
