270 BOTANICAL GAZETTE [OCTOBER 
extent affects even those plants which inhabit the higher 
mountains, but in a less degree than those which grow at lower 
altitudes. The mountain plants have a far greater need of 
protecting themselves against the low temperature of winter. 
Hence many of them are perennial herbs, which are able to 
preserve through the winter the vitality of their roots, safely 
buried in the soil, although the aerial portions perish from the 
cold. And as the air is here cooler and moister, more plants are 
found with broad and unprotected leaves than in the other areas. 
It is in these other areas that there is the greatest develop- 
ment of the protective adaptations which enable a plant most 
fully to utilize a scanty supply of water. The methods by which 
this is effected are three: by habits of growth; by provisions 
for storing supplies of water and food in times of plenty as 
reserves for times of need; and by contrivances for diminishing 
the loss of water through evaporation. 
The first of these methods is well exemplified by most of the 
xerophytic annuals. They spring up at once after light rains, 
and put forth no more than a leaf or two before proceeding to 
the production of a flower and a fruit. If moisture now fails, 
reproduction is assured; should it continue to be supplied, 
branches are sent out and flowers and seed multiplied. Thus a 
plant when receiving only a little moisture may fulfil the cycle 
of existence and provide for the continuance of its species, with- 
out attaining an inch of stature; but under more favorable con- 
ditions it may attain dimensions of two or three feet. 
The xerophytic perennial herbs make their growth in the wet 
season, and, in most cases, the aerial stems perish at the begin- 
ning of summer. Thus they reverse the seasons, remaining 
dormant in summer to survive the heat, just as in colder 
climates they remain dormant in winter in order to survive the 
cold 
The same reversal of the seasons is the habit of many of the 
deciduous shrubs. They put forth their new foliage in early 
winter, make their growth during the wet season, and, ripening 
their fruits in spring, drop their foliage when the droughts of 
summer come on, remaining leafless and dormant until its con- 
