The self-fertile form,
however, is occasionally visited, and may be crossed by insects, though
this is rather doubtful.
In my first experiments on Viola tricolor I was unsuccessful in raising
seedlings, and obtained only one full-grown crossed and self-fertilised
plant. The former was 12 1/2 inches and the latter 8 inches in height.
On the following year several flowers on a fresh plant were crossed with
pollen from another plant, which was known to be a distinct seedling;
and to this point it is important to attend. Several other flowers on
the same plant were fertilised with their own pollen. The average number
of seeds in the ten crossed capsules was 18.7, and in the twelve
self-fertilised capsules 12.83; or as 100 to 69. These seeds, after
germinating on bare sand, were planted in pairs on the opposite sides of
five pots. They were first measured when about a third of their full
size, and the crossed plants then averaged 3.87 inches, and the
self-fertilised only 2.00 inches in height; or as 100 to 52. They were
kept in the greenhouse, and did not grow vigorously. Whilst in flower
they were again measured to the summits of their stems (see Table 4/41),
with the following result:--
TABLE 4/41. Viola tricolor.
Heights of plants measured in inches.
Column 1: Number (Name) of Pot.
Column 2: Crossed Plants.
Column 3: Self-fertilised Plants.
Pot 1 : 8 2/8 : 0 2/8.
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