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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"


These facts seem to show that the short-styled plants are more fertile with
their own pollen than are the long-styled, and we shall immediately see that
this probably is the case. But I suspect that the difference in fertility
between the two forms was in this instance in part due to a distinct cause. I
repeatedly watched the flowers, and only once saw a humble-bee momentarily
alight on one, and then fly away. If bees had visited the several plants, there
cannot be a doubt that the four long-styled plants, which did not produce a
single capsule, would have borne an abundance. But several times I saw small
diptera sucking the flowers; and these insects, though not visiting the flowers
with anything like the regularity of bees, would carry a little pollen from one
form to the other, especially when growing near together; and the stigmas of the
short-styled plants, diverging within the tube of the corolla, would be more
likely than the upright stigmas of the long-styled plants, to receive a small
quantity of pollen if brought to them by small insects. Moreover from the
greater number of the long-styled than of the short-styled plants in the garden,
the latter would be more likely to receive pollen from the long-styled, than the
long-styled from the short-styled.
In 1862 I raised thirty-four plants of this Linum in a hot-bed; and these
consisted of seventeen long-styled and seventeen short-styled forms.


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