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
I raised from this union twenty-five plants, which proved to be seventeen long-
styled and eight mid-styled, but not one short-styled. None of these plants were
in the least dwarfed. I examined, during the highly favourable season of 1866,
the pollen of four plants: in one mid-styled plant, some of the anthers of the
longest stamens were contabescent, but the pollen-grains in the other anthers
were mostly sound, as they were in all the anthers of the shortest stamens; in
two other mid-styled and in one long-styled plant many of the pollen-grains were
small and shrivelled; and in the latter plant as many as a fifth or sixth part
appeared to be in this state. I counted the seeds in five plants (Numbers 26 to
30), of which two were moderately sterile and three fully fertile.
[PLANT 26.
This mid-styled plant was freely and legitimately fertilised, during the rather
unfavourable year 1864, by numerous surrounding legitimate and illegitimate
plants. It yielded an average, from ten capsules, of 83.5 seeds, with a maximum
of 110 and a minimum of 64, thus attaining 64 per cent of the normal fertility.
During the highly favourable year 1866, it was freely and legitimately
fertilised by illegitimate plants belonging to the present Class and to Class 5,
and yielded an average, from eight capsules, of 86 seeds, with a maximum of 109
and a minimum of 61, and thus attained 66 per cent of the normal fertility. This
was the plant with some of the anthers of the longest stamens contabescent as
above mentioned.
PLANT 27.
This mid-styled plant, fertilised during 1864 in the same manner as the last,
yielded an average, from ten capsules, of 99.4 seeds, with a maximum of 122 and
a minimum of 53, thus attaining to 76 per cent of the normal fertility. If the
season had been more favourable, its fertility would probably have been somewhat
greater, but, judging from the last experiment, only in a slight degree.
PLANT 28.
This mid-styled plant, when legitimately fertilised during the favourable season
of 1866, in the manner described under Number 26, yielded an average, from eight
capsules, of 89 seeds, with a maximum of 119 and a minimum of 69, thus producing
68 per cent of the full number of seeds. In the pollen of both sets of anthers,
nearly as many grains were small and shrivelled as sound.
PLANT 29.
Public-domain text, read in full here on John Shaqi.
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