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Darwin, Charles, 1809-1882

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

The anthers in many of their flowers, and in the
flowers of some other plants in the first six classes, were either contabescent
or included numerous small and shrivelled pollen-grains. As the suspicion at one
time occurred to me that the lessened fertility of the illegitimate plants might
be due to the pollen alone having been affected, I may remark that this
certainly was not the case; for several of them, when fertilised by sound pollen
from legitimate plants, did not yield the full complement of seeds; hence it is
certain that both the female and male reproductive organs were affected. In each
of the seven classes, the plants, though descended from the same parents, sown
at the same time and in the same soil, differed much in their average degree of
fertility.
Turning now to the fifth, sixth, and seventh classes, and looking to the right
hand column of Table 5.30, we find nearly as many plants with a percentage of
seeds above the normal standard as beneath it. As with most plants the number of
seeds produced varies much, it might be thought that the present case was one
merely of variability. But this view must be rejected, as far as the less
fertile plants in these three classes are concerned: first, because none of the
plants in Class 5 attained their proper height, which shows that they were in
some manner affected; and, secondly, because many of the plants in Classes 5 and
6 produced anthers which were either contabescent or included small and
shrivelled pollen-grains.


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