1895.) The Philosophy of Flower Seasons. 103 
bloom before the leaves are developed, the witch-hazel notably 
after the leaves have fallen. The leaves act in an equally 
disadvantageous way, by concealing the flowers so that insects 
do not easily find them. Before the leaves have appeared in 
the woods, the trees which depend upon insects for pol- 
lination are very conspicuous and have a good chance of 
being attended by the insects which are attracted by their 
own flowers and by the flowers of the herbaceous plants which 
grow under their protection. Later, when the woods become 
shady, there are few herbaceous flowers, and few insects to at- 
tend the trees if they should bear flowers dependent upon 
them. The rose family (Rosaceae) is of particular interest, 
since of the larger families it contains the greatest number 
of trees., and as its maximum is early (Fig. 14, Plate VIII), 
it is the only one of the entomophilous tree-producing families, 
which is in a favorable position for giving rise to aborescent 
forms. The first to bloom is the service-berry (Amelanchier), 
and the trees, e.g.,the plum, cherry, apple and hawthorn, coin- 
cide pretty nearly with the maximum of the family, though 
it is significant that the latest species are herbaceous. As the 
season advances, the flowering of trees and of herbaceous 
plants which grow under them is evidently cut short in corre- 
lation with the appearance of the overshadowing leaves.‘ 
While it is not my intention to discuss wind-pollinated 
plants specially at this time, I think that their blooming sea- 
sons may be explained by reference to their competition among 
themselves and with the insect-pollinated flora. Even in 
herbaceous plants it seems that the spring might reasonably 
be expected to be the most favorable for pollination, since 
they would be less likely to be overtopped by the later plants 
which become increasingly more luxuriant. But at different 
seasons they can readily occupy positions unfavorable to ento- 
mophilous plants, and in summer they may endure the com- 
petition of the entomophilous flora better than that of an in- 
definite number of plants depending upon the wind, or better 
* One of my favorite botanizing grounds shows a great variety of vernal flowers, 
but after the appearance of the leaves is covered by a uniform growth of the 
anemophilous wood-nettle (Laportea canadensis). 
