CLIMATIC DISTRIBUTION OF CERTAIN ANGIOSPERM LEAVES 
29 
cold-temperate flora are all southern, warm-temperate types, most of 
which are at one extremity of their range, north of their region of 
optimum development. They are : 
Among the entire-leaved shrubs and herbs there are many frigid 
and warm-temperate types that are largely confined to the northern 
or southern portions of the region respectively. 
In considering the percentages of non-entire leaves in the lowland- 
tropical flora, it is important to note that the serrations, dentations, 
etc., of the non-entire leaves, particularly of trees and shrubs, are very 
frequently vestigial or rudimentary. In fact, not only are the non- 
entire types of margins less numerous than they are in the uplands of 
southern and southeastern Brazil, but they differ from them in showing 
obvious signs of reduction. Similar contrasts have been observed 
between the plants of the uplands and the lowlands of India, Hawaii, 
Ceylon, and other tropical and subtropical areas. 
The correlations between leaf-margin and environment would 
undoubtedly be even more striking, if it were possible to study the 
"vegetation" of the temperate and tropical zones rather than their 
"flora." That is to say, if it were possible to deal with numbers of 
individuals rather than species. For example, the few entire-leaved 
woody plants in non-xerophytic cold-temperate environments and 
the comparatively limited number of non-entire woody species in 
lowland- tropical regions are represented in most cases by a relatively 
limited number of individuals. Those typical cold-temperate and 
tropical species that are most important numerically have, except in 
a few instances, leaves and leaflets with entire margins in lowland- 
tropical regions and non-entire margins in mesophytic cold-temperate 
ones. 
A second point that deserves consideration, in a discussion of the 
significance of the percentages given in Table I, is the difference in the 
relative adaptability of trees, shrubs, and herbs. Arborescent plants, 
owing to their large size and persistent aerial stems, are more directly 
exposed to prevailing climatic influences than are small shrubs and 
herbs. They are, therefore, less adaptable, and, owing to a longer 
Quercus phellos L. 
Q. imhricaria Michx. 
Cercis canadensis L. 
Nyssa sylvatica Marsh, 
Magnolia acuminata L. 
M, virginiana L. 
Gymnocladus dioica (L.) Koch. 
Diospyros virginiana L. 
