Eighteen short-styled flowers legitimately fertilised yielded, as may be seen in
Table 3.20, 15 fruits, each having on an average 2.6 seeds. Four of these fruits
contained the highest possible number of seeds, namely 4, and four other fruits
contained each 3 seeds. The 12 illegitimately fertilised short-styled flowers
yielded 7 fruits, including on an average 1.86 seed; and one of these fruits
contained the maximum number of 4 seeds. This result is very surprising in
contrast with the absolute barrenness of the long-styled flowers when
illegitimately fertilised; and I was thus led to attend carefully to the degree
of self-fertility of the short-styled plants. A plant belonging to this form and
covered by a net bore 28 flowers besides those which had been artificially
fertilised, and of all these only two produced a fruit each including a single
seed. This high degree of self-sterility no doubt depended merely on the stigmas
not receiving any pollen, or not a sufficient quantity. For after carefully
covering all the long-styled plants in my garden, several short-styled plants
were left exposed to the visits of humble-bees, and their stigmas will thus have
received plenty of short-styled pollen; and now about half the flowers, thus
illegitimately fertilised, set fruit. I judge of this proportion partly from
estimation and partly from having examined three large branches, which had borne
31 flowers, and these produced 16 fruits.
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