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Darwin, Charles, 1809-1882

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

But it is a surprising
fact in this case, and in other similar ones, that the number of the offspring
which thus reverted was not larger. The fact is rendered still more strange in
the particular instance of P. veris, for there was no reversion until four or
five generations of long-styled plants had been raised. It may be seen in both
tables that the long-styled form transmits its form much more faithfully than
does the short-styled, when both are fertilised with their own-form pollen; and
why this should be so it is difficult to conjecture, unless it be that the
aboriginal parent-form of most heterostyled species possessed a pistil which
exceeded its own stamens considerably in length. (6/8. It may be suspected that
this was the case with Primula, judging from the length of the pistil in several
allied genera (see Mr. J. Scott 'Journal of the Linnean Society Botany' volume 8
1864 page 85). Herr Breitenbach found many specimens of Primula elatior growing
in a state of nature with some flowers on the same plant long-styled, others
short-styled and others equal-styled; and the long-styled form greatly
preponderated in number; there being 61 of this form to 9 of the short-styled
and 15 of the equal-styled.) I will only add that in a state of nature any
single plant of a trimorphic species no doubt produces all three forms; and this
may be accounted for either by its several flowers being separately fertilised
by both the other forms, as Hildebrand supposes; or by pollen from both the
other forms being deposited by insects on the stigma of the same flower.


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