The Different Forms of Flowers on Plants of the Same SpeciesDarwin, Charles
Science
The Different Forms of Flowers on Plants of the Same Species
Darwin, Charles
Fertilization of plants; Heterostylism; Plant physiology; Plants -- Variation; Pollination
This long-styled plant was allowed during 1863 to be freely and legitimately
fertilised by an adjoining illegitimate mid-styled plant, but it did not yield a
single seed-capsule. It was then removed and planted in a remote place close to
a brother long-styled plant Number 2, so that it must have been freely though
illegitimately fertilised; under these circumstances it did not yield during
1864 and 1865 a single capsule. I should here state that a legitimate or
ordinary long-styled plant, when growing isolated, and freely though
illegitimately fertilised by insects with its own pollen, yielded an immense
number of capsules, which contained on an average 21.5 seeds.
PLANT 2.
This long-styled plant, after flowering during 1863 close to an illegitimate
mid-styled plant, produced less than twenty capsules, which contained on an
average between four and five seeds. When subsequently growing in company with
Number 1, by which it will have been illegitimately fertilised, it yielded in
1866 not a single capsule, but in 1865 it yielded twenty-two capsules: the best
of these, fifteen in number, were examined; eight contained no seed, and the
remaining seven contained on an average only three seeds, and these seeds were
so small and shrivelled that I doubt whether they would have germinated.
PLANTS 3 AND 4.
These two long-styled plants, after being freely and legitimately fertilised
during 1863 by the same illegitimate mid-styled plant as in the last case, were
as miserably sterile as Number 2.
PLANT 5.
This long-styled plant, after flowering in 1863 close to an illegitimate mid-
styled plant, yielded only four capsules, which altogether included only five
seeds. During 1864, 1865, and 1866, it was surrounded either by illegitimate or
legitimate plants of the other two forms; but it did not yield a single capsule.
It was a superfluous experiment, but I likewise artificially fertilised in a
legitimate manner twelve flowers; but not one of these produced a capsule; so
that this plant was almost absolutely barren.
PLANT 6.
This long-styled plant, after flowering during the favourable year of 1866,
surrounded by illegitimate plants of the other two forms, did not produce a
single capsule.
PLANT 7.
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