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Darwin, Charles, 1809-1882

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

They appeared at first sight grandly heterostyled,
as the stigma of the long-styled form projects far out of the corolla, whilst
the anthers are seated halfway down within the tube; whereas in the short-styled
form the anthers project from the corolla and the stigma is enclosed in the tube
at nearly the same level with the anthers of the other form. The pistil of the
long-styled is to that of the short-styled as 100 to 60 in length, and the
stigmas, taken by themselves, as 100 to 55. Nevertheless, this plant cannot be
heterostyled. The anthers in the long-styled form are brown, tough, and fleshy,
and less than half the length of those in the short-styled form, strictly as 44
to 100; and what is much more important, they were in a rudimentary condition in
the two flowers examined by me, and did not contain a single grain of pollen. In
the short-styled form, the divided stigma, which as we have seen is much
shortened, is thicker and more fleshy than the stigma of the long-styled, and is
covered with small irregular projections, formed of rather large cells. It had
the appearance of having suffered from hyperthrophy, and is probably incapable
of fertilisation. If this be so the plant is dioecious, and judging from the two
species previously described, it probably was once heterostyled, and has since
been rendered dioecious by the pistil in the one form, and the stamens in the
other having become functionless and reduced in size.


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