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Darwin, Charles, 1809-1882

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

It thus appears, as far as can be
judged from such imperfect data, that there is some connection between the
separation of the sexes in plants and the watery nature of the sites which they
inhabit; but that this does not hold good with heterostyled species.)
When I first began to experimentise on heterostyled plants it was under the
impression that they were tending to become dioecious; but I was soon forced to
relinquish this notion, as the long-styled plants of Primula which, from
possessing a longer pistil, larger stigma, shorter stamens with smaller pollen-
grains, seemed to be the more feminine of the two forms, yielded fewer seeds
than the short-styled plants which appeared to be in the above respects the more
masculine of the two. Moreover, trimorphic plants evidently come under the same
category with dimorphic, and the former cannot be looked at as tending to become
dioecious. With Lythrum salicaria, however, we have the curious and unique case
of the mid-styled form being more feminine or less masculine in nature than the
other two forms. This is shown by the large number of seeds which it yields in
whatever manner it may be fertilised, and by its pollen (the grains of which are
of smaller size than those from the corresponding stamens in the other two
forms) when applied to the stigma of any form producing fewer seeds than the
normal number.


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