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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

In all four pots a
crossed plant flowered before any one of the self-fertilised plants, and
this is usually a safe indication of some real superiority in the
crossed plants. The flowers on the parent-plants which were crossed with
pollen from another plant yielded seeds compared with the
self-fertilised flowers in the ratio of 100 to 72. We may therefore draw
the same conclusion as in the last case with respect to a cross being
decidedly beneficial.
9. Borago officinalis.
Only four crossed and four self-fertilised plants were raised and
measured, and the former were to the latter in height as 100 to 102. So
small a number of measurements ought never to be trusted; and in the
present instance the advantage of the self-fertilised over the crossed
plants depended almost entirely on one of the self-fertilised plants
having grown to an unusual height. All four crossed plants flowered
before their self-fertilised opponents. The cross-fertilised flowers on
the parent-plants in comparison with the self-fertilised flowers yielded
seeds in the proportion of 100 to 60. So that here again we may draw the
same conclusion as in the two last cases.
10. Passiflora gracilis.
Only two crossed and two self-fertilised plants were raised; and the
former were to the latter in height as 100 to 104. On the other hand,
fruits from the cross-fertilised flowers on the parent-plants contained
seeds in number, compared with those from the self-fertilised flowers,
in the proportion of 100 to 85.


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