THE FLORA 397 
the vegetation are protections not against cold, but 
against dryness. Even with an abundance of moisture in 
the soil, it may not be readily available for the plant. The 
soil is cold, the bogs are rich in humous acids, the water of 
the shores is full of soluble salts. All these conditions, 
which are the prevailing ones throughout the northern 
country, are unfavourable to the ready absorption of water 
by the plant, and hence lead to physiological dryness. 
This is further increased by the lack of protection against 
drying winds, which tend to produce strong transpiration. 
A plant whose water supply is limited, whether in wet or in 
dry soil, must guard against too great transpiration, espe- 
cially under conditions where this tends to be large. It 
hence assumes a xerophilous structure, or one fitted to con- 
tend with physiological dryness. In this respect the flora 
of Arctic climates, of alpine heights, of bogs, of sea-shore, 
and of deserts will closely resemble one another, though the 
particular devices adopted may vary with different con- 
ditions. 
Except in the rarer situations of sheltered valleys or 
sunny slopes, with relatively warmer soil, water free from 
acids, and protection from wind, the flora of Labrador may 
be considered as universally adopting one form or another 
of the various means fitted to protect it from too great 
dryness. It becomes an absorbingly interesting study to 
observe the different ways in which this object is accom- 
plished. The most evident devices are the following : — 
1. A well-developed system of roots for the absorption 
of nutrient materials and of water. 
2. A low and often stunted growth. This characteristic, 
as a special modification, applies of course to plants that 
