144 PLANT LIFE 
special adaptation to tide it over the dry, and 
often hot, time of year it would be unable 
to occupy such climatal regions. Often the 
adaptation is fairly obvious. Thus, when the 
rain falls on the South African veldt, in- 
numerable leaves and flowers spring up as if 
by magic. They flower and fruit, and then 
disappear for the rest of the year. A re- 
latively large proportion of this vegetation 
consists of perennial plants of a bulbous 
or tuberous character. As long as the dry 
weather lasts they remain in a resting condi- 
tion, the bulbs or tubers showing no sign of 
life. If they be cut open, they are found, even 
at this season, to be juicy; that is to say, they 
store water and retain it with great tenacity. 
When conditions become favourable, the 
leaves rapidly develop, and they are often not 
at all the leathery or even succulent structures 
one might expect to meet with. In fact they 
frequently resemble those of typically meso- 
phytic vegetation, and are thus _ simply 
adapted for an average water supply, and 
indeed such conditions do actually prevail 
during their period of active growth. Their 
food manufacture goes on rapidly, and the 
surplus is stored up in the swollen portion, 
so that when the growing, moist season is 
over, they will have accumulated an amount 
of easily utilisable food. It is the possession 
of these qualities which enables them to 
form underground the flowers and leaves 
which will expand so rapidly on the return 
