PIPER FLORA OF THE STATE OF WASHINGTON. 65 



Distribution of characteristic Arctic-Alpine species — Continued. 



REGIONS OF PECULIAR BOTANIC INTEREST. 



In a State where conditions are so diverse as in Washington, and 

 where practically every locality that has been carefully explored 

 contains species of apparently very limited range, it is difficult to say 

 which places have transcendent botanical interest. Where, however, 

 the local massing of species of narrow range can be associated with 

 more or less definite environmental conditions, the phenomenon is 

 worth especial consideration. The following areas thus deserves 

 special attention. 



THE OLYMPIC MOUNTAINS. 



The most striking peculiarities as regards these mountains, botan- 

 ically considered, are the excessive rainfall on their southern and 

 western slopes, and their isolated position. The heavy moisture 

 precipitation results in modifying greatly the effect of altitude, so 

 that the lines of zonal demarcation are much obscured. Many Humid 

 29418—06 M 5 



