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
From the doubts caused by the two first trials, in which it was not
known with certainty that the plants had been crossed; and from the
crossed plants in the last experiment having been put into competition
with plants self-fertilised for three generations, which moreover grew
very unequally, I resolved to repeat the trial on a larger scale, and in
a rather different manner. I obtained seeds of the same crimson variety
of Iberis umbellata from another nursery garden, and raised plants from
them. Some of these plants were allowed to fertilise themselves
spontaneously under a net; others were crossed by pollen taken from
plants raised from seed sent me by Dr. Durando from Algiers, where the
parent-plants had been cultivated for some generations. These latter
plants differed in having pale pink instead of crimson flowers, but in
no other respect. That the cross had been effective (though the flowers
on the crimson mother-plant had NOT been castrated) was well shown when
the thirty crossed seedlings flowered, for twenty-four of them produced
pale pink flowers, exactly like those of their father; the six others
having crimson flowers exactly like those of their mother and like those
of all the self-fertilised seedlings. This case offers a good instance
of a result which not rarely follows from crossing varieties having
differently coloured flowers; namely, that the colours do not blend, but
resemble perfectly those either of the father or mother plant. The seeds
of both lots, after germinating on sand, were planted on opposite sides
of eight pots. When fully grown, the plants were measured to the summits
of the flower-heads, as shown in Table 4/32.
TABLE 4/32. Iberis umbellata.
Height of Plants to the summits of the flower-heads, measured in inches:
0 signifies that the Plant died.
Column 1: Number (Name) of Pot.
Column 2: Plants from a Cross with a fresh Stock.
Column 3: Plants from Spontaneously Self-fertilised Seeds.
Pot 1 : 18 6/8 : 17 3/8.
Pot 1 : 17 5/8 : 16 7/8.
Pot 1 : 17 6/8 : 13 1/8.
Pot 1 : 20 1/8 : 15 3/8.
Pot 2 : 20 2/8 : 0.
Pot 2 : 15 7/8 : 16 6/8.
Pot 2 : 17 : 15 2/8.
Pot 3 : 19 2/8 : 13 6/8.
Pot 3 : 18 1/8 : 14 2/8.
Pot 3 : 15 2/8 : 13 4/8.
Pot 4 : 17 1/8 : 16 4/8.
Pot 4 : 18 7/8 : 14 4/8.
Pot 4 : 17 5/8 : 16.
Pot 4 : 15 6/8 : 15 3/8.
Pot 4 : 14 4/8 : 14 7/8.
Pot 5 : 18 1/8 : 16 4/8.
Pot 5 : 14 7/8 : 16 2/8.
Pot 5 : 16 2/8 : 14 2/8.
Pot 5 : 15 5/8 : 14 2/8.
Pot 5 : 12 4/8 : 16 1/8.
Pot 6 : 18 6/8 : 16 1/8.
Pot 6 : 18 6/8 : 15.
Pot 6 : 17 3/8 : 15 2/8.
Pot 7 : 18 : 16 3/8.
Pot 7 : 16 4/8 : 14 4/8.
Pot 7 : 18 2/8 : 13 5/8.
Pot 8 : 20 6/8 : 15 6/8.
Pot 8 : 17 7/8 : 16 3/8.
Pot 8 : 13 5/8 : 20 2/8.
Pot 8 : 19 2/8 : 15 6/8.
Total : 520.38 : 449.88.
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