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Darwin, Charles, 1809-1882

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

Exactly the same thing occurs with the
two forms of a heterostyled species. Thus several long-styled flowers of Primula
veris were fertilised illegitimately with pollen from another plant of the same
form, and twenty-four hours afterwards legitimately with pollen from a short-
styled dark-red polyanthus which is a variety of P. veris; and the result was
that every one of the thirty seedlings thus raised bore flowers more or less
red, showing plainly how prepotent the legitimate pollen from a short-styled
plant was over the illegitimate pollen from a long-styled plant.
In all the several foregoing points the parallelism is wonderfully close between
the effects of illegitimate and hybrid fertilisation. It is hardly an
exaggeration to assert that seedlings from an illegitimately fertilised
heterostyled plant are hybrids formed within the limits of one and the same
species. This conclusion is important, for we thus learn that the difficulty in
sexually uniting two organic forms and the sterility of their offspring, afford
no sure criterion of so-called specific distinctness. If any one were to cross
two varieties of the same form of Lythrum or Primula for the sake of
ascertaining whether they were specifically distinct, and he found that they
could be united only with some difficulty, that their offspring were extremely
sterile, and that the parents and their offspring resembled in a whole series of
relations crossed species and their hybrid offspring, he might maintain that his
varieties had been proved to be good and true species; but he would be
completely deceived.


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