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
The results may be given in another form (Table 1.7) by comparing, first, the
number of capsules, whether good or bad, or of the good alone, produced by 100
flowers of both forms when legitimately and illegitimately fertilised; secondly,
by comparing the weight of seed in 100 of these capsules, whether good or bad;
or, thirdly, in 100 of the good capsules.
TABLE 1.7. Primula veris.
Column 1: Nature of the Union.
Column 2: Number of Flowers fertilised.
Column 3: Number of Capsules.
Column 4: Number of good Capsules.
Column 5: Weight of Seed in grains.
...
Column 6: Number of Capsules.
Column 7: Weight of Seed in grains.
...
Column 8: Number of good Capsules.
Column 9: Weight of Seed in grains.
The two legitimate unions :
100 : 77 : 71 : 39 :: 100 : 50 :: 100 : 54.
The two illegitimate unions :
100 : 45 : 31 : 11 :: 100 : 24 :: 100 : 35.
We here see that the long-styled flowers fertilised with pollen from the short-
styled yield more capsules, especially good ones (i.e. containing more than one
or two seeds), and that these capsules contain a greater proportional weight of
seeds than do the flowers of the long-styled when fertilised with pollen from a
distinct plant of the same form. So it is with the short-styled flowers, if
treated in an analogous manner. Therefore I have called the former method of
fertilisation a legitimate union, and the latter, as it fails to yield the full
complement of capsules and seeds, an illegitimate union. These two kinds of
union are graphically represented in Figure 1.2.
(FIGURE 1.2. Primula veris.
Graphic representation of two kinds of union between:
Left: Long-styled form.
Right: Short-styled form.)
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