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Darwin, Charles, 1809-1882

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

The former bore 289 flowers, of which 186 (i.e. 64 per cent) had set
fruit, yielding 1.88 seed per fruit. The ten short-styled plants bore 373
flowers, of which 262 (i.e. 70 per cent) had set fruit, yielding 1.86 seed per
fruit. So that the short-styled plants produced many more flowers, and these set
a rather larger proportion of fruit, but the fruits themselves yielded a
slightly lower average number of seeds than did the long-styled plants. The
results of Hildebrand's experiments on the fertility of the two forms are given
in Table 3.19.
TABLE 3.19. Pulmonaria officinalis (from Hildebrand).
Column 1: Nature of the Union.
Column 2: Number of Flowers fertilised.
Column 3: Number of Fruits produced.
Column 4: Average Number of Seeds per Fruit.
Long-styled by pollen of short-styled. Legitimate union :
14 : 10 : 1.30.
Long-styled 14 by own-pollen, and 16 by pollen of other plant of same form.
Illegitimate union :
30 : 0 : 0.
Short-styled by pollen of long-styled. Legitimate union:
16 : 14 : 1.57.
Short-styled 11 by own-pollen, 14 by pollen of other plant of same form.
Illegitimate union :
25 : 0 : 0.
In the summer of 1864, before I had heard of Hildebrand's experiments, I noticed
some long-styled plants of this species (named for me by Dr. Hooker) growing by
themselves in a garden in Surrey; and to my surprise about half the flowers had
set fruit, several of which contained 2, and one contained even 3 seeds.


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