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1899 | VEGETATION OF TROPICAL AMERICA per 
remain on the trees. But how long time a tree will keep its 
leaves depends partly upon the physical conditions, hence the 
same species in other conditions more favorable for the life of 
plants may keep its leaves longer. In the tropical forests, with 
their uniform physical conditions, the leaves may live much 
longer, though most of them are not able to live for more than 
one year, and only a few may remain for two years. They do 
not fall before new leaves have appeared, but none of them is 
able to reach the age of the acicular leaves of our pine trees. 
This long duration of the old leaves causes the almost unaltered 
dark hues of the tropical forest. 
During my last journey in the tropics one of the charac- 
teristics of the forest trees that attracted my attention was the 
frequency of highly glistening leaves. Everyone knows the glis- 
tening leaves of the rubber tree, /écus elastica, and of our own 
Christ’s thorn, //ex Aguifolium, and in some smaller degree of other 
trees, though most generally the leaves of our trees are dull 
green. In the tropics the gloss of the leaves is much more 
marked; everywhere one may see the dark green leaves reflect 
the light, and even such plants as the cocoa tree, the plantain, 
the Indian corn, and the sugar cane have something of that gloss 
which is especially associated with the dark green, stiff, and 
leathery, long-lived leaf. Of course, this gloss depends upon 
certain anatomical structures, and it seems to be, directly or 
indirectly, a defense against too intense light. 
Another fact that gives the tropical forest an aspect different 
from that of our own forests of foliiferous trees is the large, bright 
spots of yellow, white, red, purple, and other tints that from 
time to time are to be seen here and there, when one or another 
of the woody plants or climbers is in blooming and covers itself 
with flowers out of number. This phenomenon shows us both 
the sparseness of the individuals and to what degree the flower- 
ing of every species is fixed to a certain time of the year. It is 
said that almost all species are flowering all the year round, but 
this is unquestionably an error. An explanation of this mis- 
statement we find in the fact that different species have a differ- 
