The Different Forms of Flowers on Plants of the Same SpeciesDarwin, Charles
Science
The Different Forms of Flowers on Plants of the Same Species
Darwin, Charles
Fertilization of plants; Heterostylism; Plant physiology; Plants -- Variation; Pollination
With respect to Mr. Duck’s lot in Table 5.31, seed was saved from a single
plant, of which the form was not observed, and this produced nine equal-styled
and twenty long-styled plants. The equal-styled resembled in all respects those
previously described; and eight of their capsules spontaneously self-fertilised
contained on an average 44.4 seeds, with a maximum of 61 and a minimum of 23. In
regard to the twenty long-styled plants, the pistil in some of the flowers did
not project quite so high as in ordinary long-styled flowers; and the stigmas,
though properly elongated, were smooth; so that we have here a slight approach
in structure to the pistil of the short-styled form. Some of these long-styled
plants also approached the equal-styled in function; for one of them produced no
less than fifteen spontaneously self-fertilised capsules, and of these eight
contained, on an average, 31.7 seeds, with a maximum of 61. This average would
be rather low for a long-styled plant artificially fertilised with its own
pollen, but is high for one spontaneously self-fertilised. For instance, thirty-
four capsules produced by the illegitimate grandchildren of a long-styled plant,
spontaneously self-fertilised, contained on an average only 9.1 seeds, with a
maximum of 46. Some seeds indiscriminately saved from the foregoing twenty-nine
equal-styled and long-styled plants produced sixteen seedlings, grandchildren of
the original plant belonging to Mr. Duck; and these consisted of fourteen equal-
styled and two long-styled plants; and I mention this fact as an additional
instance of the transmission of the equal-styled variety.
The third lot in Table 5.31, namely the Baston plants, are the last which need
be mentioned. The long and short-styled plants, and the fifteen equal-styled
plants, were descended from two distinct stocks. The latter were derived from a
single plant, which the gardener is positive was not long-styled; hence,
probably, it was equal-styled. In all these fifteen plants the anthers,
occupying the same position as in the long-styled form, closely surrounded the
stigma, which in one instance alone was slightly elongated. Notwithstanding this
position of the stigma, the flowers, as the gardener assured me, did not yield
many seeds; and this difference from the foregoing cases may perhaps have been
caused by the pollen being bad, as in some of the Southampton equal-styled
plants.]
CONCLUSIONS WITH RESPECT TO THE EQUAL-STYLED VARIETY OF P. Sinensis.
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