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Darwin, Charles, 1809-1882

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

The ovules in both
kinds of males are in an aborted condition. On my mentioning this case to
Professor Caspary, he examined several male plants in the botanic gardens at
Konigsberg, where there were no females, and sent me the drawings in Figure
7.13.
In the English plants the petals are not so greatly reduced as represented in
this drawing. My son observed that those males which had their pistils
moderately well-developed bore slightly larger flowers, and, what is very
remarkable, their pollen-grains exceeded by a little in diameter those of the
males with greatly reduced pistils. This fact is opposed to the belief that the
present species was once heterostyled; for in this case it might have been
expected that the shorter-styled plants would have had larger pollen-grains.
In the female plants the stamens are in an extremely rudimentary condition, much
more so than the pistils in the males. The pistil varies considerably in length
in the female plants, so that they may be divided into two sub-forms according
to the length of this organ. Both the petals and sepals are decidedly smaller in
the females than in the males; and the sepals do not turn downwards, as do those
of the male flowers when mature. All the flowers on the same male or same female
bush, though subject to some variability, belong to the same sub-form; and as my
son never experienced any difficulty in deciding under which class a plant ought
to be included, he believes that the two sub-forms of the same sex do not
graduate into one another.


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