28 A Study of the Vegetation of 
this station was intermediate in xerophytism, as expressed by the 
evaporating power of the air, between the two stations in the 
pines. A second station in the shrub on the north slope of the 
butte and near the western end was maintained in a dense growth 
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Fic. 6. Evaporation rates in the various plant communities on Kamiak 
Mountain, and in the Pine consocies (graph 4) at Viola, Idaho. 
of Opulaster-Ceanothus chaparral. The evaporation rates, not 
shown in the chart, were much lower, often being less than those 
in the fir-tamarack forest. In fact, it is not difficult to find situa- 
tions in which shrubby growth is so dense as to greatly retard 
evaporation and reduce the light to a point where pine seedlings 
can not grow. 
28 
