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Darwin, Charles, 1809-1882

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


EQUAL-STYLED VARIETIES.
The tendency of the dimorphic species of Primula to produce equal-styled
varieties deserves notice. Cases of this kind have been observed, as shown in
the last chapter, in no less than six species, namely, P. veris, vulgaris,
Sinensis, auricula, farinosa, and elatior. In the case of P. veris, the stamens
resemble in length, position and size of their pollen-grains the stamens of the
short-styled form; whilst the pistil closely resembles that of the long-styled,
but as it varies much in length, one proper to the short-styled form appears to
have been elongated and to have assumed at the same time the functions of a
long-styled pistil. Consequently the flowers are capable of spontaneous self-
fertilisation of a legitimate nature and yield a full complement of seed, or
even more than the number produced by ordinary flowers legitimately fertilised.
With P. Sinensis, on the other hand, the stamens resemble in all respects the
shorter ones proper to the long-styled form, whilst the pistil makes a near
approach to that of the short-styled, but as it varies in length, it would
appear as if a long-styled pistil had been reduced in length and modified in
function. The flowers in this case as in the last are capable of spontaneous
legitimate fertilisation, and are rather more productive than ordinary flowers
legitimately fertilised.


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