CHAPTER XXVIII 
ECOLOGY OF FLOWERS 
422. Topics of the Chapter. — The ecology of flowers is 
concerned mainly with the means by which the transfei- 
ence of pollen or pollination is effected, and with the ways 
in which pollen is kept away from undesirable insect 
visitors and from rain. 
423. Cross-Pollination and Self-Pollination.—It was 
long supposed by botanists that the pollen of any perfect 
flower needed only to be placed on the stigma of the same 
flower to insure satisfactory fertilization. But in 1857 
and 1858 the great English naturalist, Charles Darwin, 
stated that certain kinds of flowers were entirely dependent 
for fertilization on the transference of pollen from one 
plant to another, and he and other botanists soon extended 
the list of such flowers until it came to include most of 
the showy, sweet-scented, or otherwise conspicuous kinds. 
It was also shown that probably nearly all attractive 
flowers, even if they can produce some seed when self- 
pollinated, do far better when pollinated from the flowers 
of another plant of the same kind! This important fact 
was established by a long series of experiments on the 
number and vitality of seeds produced by a flower when 
treated with its own pollen, or self-pollinated, and when 
1 See Darwin’s Cross and Self-Fertilization in the Vegetable Kingdom 
(especially Chapters I and II). 
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