The Effects of Cross & Self-Fertilisation in the Vegetable KingdomDarwin, Charles
Science
The Effects of Cross & Self-Fertilisation in the Vegetable Kingdom
Darwin, Charles
Fertilization of plants; Plants -- Variation; Pollination
The eight crossed plants here average 30.78, and the eight
self-fertilised 25.21 inches in height; or as 100 to 82. These plants
were left uncovered in the greenhouse to set their pods, but they
produced very few good ones, perhaps in part owing to few bees visiting
them. The crossed plants produced nine pods, containing on an average
3.4 seeds, and the self-fertilised plants seven pods, containing on an
average 3 seeds, so that the seeds from an equal number of plants were
as 100 to 88.
Two other crossed seedlings, each with two self-fertilised seedlings on
the opposite sides of the same large pot, were turned out of their pots
early in the season, without being disturbed, into open ground of good
quality. They were thus subjected to but little competition with one
another, in comparison with the plants in the above three pots. In the
autumn the two crossed plants were about 3 inches taller than the four
self-fertilised plants; they looked also more vigorous and produced many
more pods.
Two other crossed and self-fertilised seeds of the same lot, after
germinating on sand, were planted on the opposite sides of a large pot,
in which a Calceolaria had long been growing, and were therefore exposed
to unfavourable conditions: the two crossed plants ultimately attained a
height of 20 1/2 and 20 inches, whilst the two self-fertilised were only
18 and 9 1/2 inches high.
Lupinus pilosus.
From a series of accidents I was again unfortunate in obtaining a
sufficient number of crossed seedlings; and the following results would
not be worth giving, did they not strictly accord with those just given
with respect to Lupinus luteus. I raised at first only a single crossed
seedling, which was placed in competition with two self-fertilised ones
on the opposite side of the same pot. These plants, without being
disturbed, were soon afterwards turned into the open ground. By the
autumn the crossed plant had grown to so large a size that it almost
smothered the two self-fertilised plants, which were mere dwarfs; and
the latter died without maturing a single pod. Several self-fertilised
seeds had been planted at the same time separately in the open ground;
and the two tallest of these were 33 and 32 inches, whereas the one
crossed plant was 38 inches in height. This latter plant also produced
many more pods than did any one of the self-fertilised plants, although
growing separately. A few flowers on the one crossed plant were crossed
with pollen from one of the self-fertilised plants, for I had no other
crossed plant from which to obtain pollen. One of the self-fertilised
plants having been covered by a net produced plenty of spontaneously
self-fertilised pods.
CROSSED AND SELF-FERTILISED PLANTS OF THE SECOND GENERATION.
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