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 ensuing winter was very severe, and in the following spring (1871)
the plants were again examined. All the self-fertilised were now dead,
with the exception of a single branch on one plant, which bore on its
summit a minute rosette of leaves about as large as a pea. On the other
hand, all the crossed plants without exception were growing vigorously.
So that the self-fertilised plants, besides their inferiority in other
respects, were more tender.
Another experiment was now tried for the sake of ascertaining how far
the superiority of the crossed plants, or to speak more correctly, the
inferiority of the self-fertilised plants, would be transmitted to their
offspring. The one crossed and one self-fertilised plant, which were
first raised, had been turned out of their pot and planted in the open
ground. Both produced an abundance of very fine capsules, from which
fact we may safely conclude that they had been cross-fertilised by
insects. Seeds from both, after germinating on sand, were planted in
pairs on the opposite sides of three pots. The naturally crossed
seedlings derived from the crossed plants flowered in all three pots
before the naturally crossed seedlings derived from the self-fertilised
plants. When both lots were in full flower, the two tallest plants on
each side of each pot were measured, and the result is shown in Table
4/42.
TABLE 4/42. Viola tricolor: seedlings from crossed and self-fertilised
plants, the parents of both sets having been left to be naturally
fertilised.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Naturally Crossed Plants from artificially crossed Plants.
Column 3: Naturally Crossed Plants from Self-fertilised Plants.
Pot 1 : 12 1/8 : 9 6/8.
Pot 1 : 11 6/8 : 8 3/8.
Pot 2 : 13 2/8 : 9 6/8.
Pot 2 : 10 : 11 4/8.
Pot 3 : 14 4/8 : 11 1/8.
Pot 3 : 13 6/8 : 11 3/8.
Total : 75.38 : 61.88.
The average height of the six tallest plants derived from the crossed
plants is 12.56 inches; and that of the six tallest plants derived from
the self-fertilised plants is 10.31 inches; or as 100 to 82. We here see
a considerable difference in height between the two sets, though very
far from equalling that in the previous trials between the offspring
from crossed and self-fertilised flowers. This difference must be
attributed to the latter set of plants having inherited a weak
constitution from their parents, the offspring of self-fertilised
flowers; notwithstanding that the parents themselves had been freely
intercrossed with other plants by the aid of insects.
10. RANUNCULACEAE.--Adonis aestivalis.
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