But it does not follow from this, that they would not
be cross by the aid of other and larger insects in their native country,
which in botanical works is said to be the south of Europe and the East
Indies. Accordingly I wrote to Professor Delpino, in Florence, and he
informs me "that it is the fixed opinion of gardeners there that the
varieties do intercross, and that they cannot be preserved pure unless
they are sown separately."
It follows also from the foregoing facts that the several varieties of
the sweet-pea must have propagated themselves in England by
self-fertilisation for very many generations, since the time when each
new variety first appeared. From the analogy of the plants of Mimulus
and Ipomoea, which had been self-fertilised for several generations, and
from trials previously made with the common pea, which is in nearly the
same state as the sweet-pea, it appeared to me very improbable that a
cross between the individuals of the same variety would benefit the
offspring. A cross of this kind was therefore not tried, which I now
regret. But some flowers of the Painted Lady, castrated at an early age,
were fertilised with pollen from the Purple sweet-pea; and it should be
remembered that these varieties differ in nothing except in the colour
of their flowers. The cross was manifestly effectual (though only two
seeds were obtained), as was shown by the two seedlings, when they
flowered, closely resembling their father, the Purple pea, excepting
that they were a little lighter coloured, with their keels slightly
streaked with pale purple.
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