CHAPTER XIV 
FLOWERS AND INSECTS 
144. Pollination. —Among Gymnosperms the pollen is 
transferred by the wind, and this is true also of many 
Angiosperms. But the prevailing method of pollination 
among Angiosperms is the use of insects as the agents of 
transfer. This mutually helpful relation between flowers 
and insects is a very remarkable one, and in some cases 
it has become so intimate that they cannot exist without 
each other. Flowers are modified in many ways in rela- 
tion to insect visits, and insects are variously adapted to 
flowers. 
The pollen may be transferred to the stigma of its own 
flower (self-pollination), or to the stigma of some other 
flower of the same kind (cross-pollination). In the latter 
case the two flowers concerned may be upon the same 
plant or upon different plants, which may be quite distant 
from one another. Since flowers are very commonly ar- 
ranged to secure cross-pollination, it must be more advan- 
tageous in general than self-pollination. 
The advantage of this relation to the insect is to secure 
food. This the flower provides in the form of either nectar 
or pollen; and insects visiting flowers may be grouped as 
nectar-feeders, represented by moths and butterflies, and 
pollen-feeders, represented by the numerous bees and wasps. 
The presence of these supplies of food in the flower is made 
known to the insect by the display of color, by odor, or by 
form. It should be said that the attraction of insects to 
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