If no pollen is enclosed
between the lips, these open again after a time. Mr. Kitchener has
ingeniously explained the use of these movements, namely, to prevent the
self-fertilisation of the flower. (3/2. 'A Year's Botany' 1874 page
118.) If a bee with no pollen on its back enters a flower it touches the
stigma, which quickly closes, and when the bee retires dusted with
pollen, it can leave none on the stigma of the same flower. But as soon
as it enters any other flower, plenty of pollen is left on the stigma,
which will be thus cross-fertilised. Nevertheless, if insects are
excluded, the flowers fertilise themselves perfectly and produce plenty
of seed; but I did not ascertain whether this is effected by the stamens
increasing in length with advancing age, or by the bending down of the
pistil. The chief interest in my experiments on the present species,
lies in the appearance in the fourth self-fertilised generation of a
variety which bore large peculiarly-coloured flowers, and grew to a
greater height than the other varieties; it likewise became more highly
self-fertile, so that this variety resembles the plant named Hero, which
appeared in the sixth self-fertilised generation of Ipomoea.
Some flowers on one of the plants raised from the purchased seeds were
fertilised with their own pollen; and others on the same plant were
crossed with pollen from a distinct plant.
Pages:
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110