FERTILIZATION. 161 
ears or none at all. The common ragweed, another moncecious 
plant, is remarkable for the great quantities of pollen which 
shake off it on to the shoes or clothes of the passer-by, and it 
is wind-fertilized. So, too, are the monecious pines, and 
these produce so much pollen that it has been mistaken for 
showers of sulphur, falling often at long distances from the 
woods where it was produced. The pistil of wind-fertilized 
flowers is often feathery and thus adapted to catch flying 
pollen-grains (Fig. 148). Other char- 
acteristics of such flowers are the 
inconspicuous character of their flow- 
ers, Which are usually green or green- 
ish, the absence of odor and of 
nectar, the regularity of the corolla, ‘Fue. 143. — Pistil of a Grass. 
and the appearance of the flowers 4@, ovary; 6, feathery stigma, 
adapted for wind-fertiliza- 
before the leaves or their occurrence Han 
on stalks raised above the leaves. 
Pollen is, in the case of a few aquatic plants, carried from 
flower to flower by the water on which it floats. 
198. Insect-Fertilized Flowers. — Most plants which require 
cross-fertilization depend upon insects as pollen-carriers,* and 
it may be stated as a general fact that the showy colors and 
markings of flowers and their odors, all serve as so many 
advertisements of the nectar (commonly but wrongly called 
honey), or of the nourishing pollen which the flower has to 
offer to insect-visitors. | 
Many insects depend mainly or wholly upon the nectar and 
the pollen of flowers for their food. Such insects usually 
visit during the day only one kind of flower, and therefore 
carry but one kind of pollen. Going straight from one flower 
to another with this, they evidently waste far less pollen than 
the wind or water must waste. It is therefore clearly 
advantageous to flowers to develop such adaptations as fit 
1A few are fertilized by snails ; many more by humming-birds and other birds. 
