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Darwin, Charles, 1809-1882

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

In short, without entering on further details, there is
a close general correspondence in structure between this species and L.
salicaria, but with some differences in the proportional lengths of the parts.
The fact of each of the three pistils having two sets of stamens of
corresponding lengths, borne by the two other forms, comes out conspicuously. In
the mid-styled form the pollen-grains from the longest stamens are nearly double
the diameter of those from the shortest stamens; so that there is a greater
difference in this respect than in L. salicaria. In the long-styled form, also,
the difference in diameter between the pollen-grains of the mid-length and
shortest stamens is greater than in L. salicaria. These comparisons, however,
must be received with caution, as they were made on specimens soaked in water
after having been long kept dry.
Lythrum thymifolia.
This form, according to Vaucher, is dimorphic, like Primula, and therefore
presents only two forms. (4/8. 'Hist. Phys. des Plantes d'Europe' tome 2 1841
pages 369, 371.) I received two dried flowers from Kew, which consisted of the
two forms; in one the stigma projected far beyond the calyx, in the other it was
included within the calyx; in this latter form the style was only one-fourth of
the length of that in the other form. There are only six stamens; these are
somewhat graduated in length, and their anthers in the short-styled form stand a
little above the stigma, but yet by no means equal in length the pistil of the
long-styled form.


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