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Darwin, Charles, 1809-1882

"Effects of Cross and Self Fertilisation in the Vegetable Kingdom"

I would instance Christine as an example of this fact." We have
here an interesting case of variability in an important functional
point.) Some flowers on a common scarlet variety were self-fertilised,
and other flowers were crossed with pollen from another plant; but no
sooner had I done so, than I remembered that these plants had been
propagated by cuttings from the same stock, and were therefore parts in
a strict sense of the same individual. Nevertheless, having made the
cross I resolved to save the seeds, which, after germinating on sand,
were planted on the opposite sides of three pots. In one pot the
quasi-crossed plant was very soon and ever afterwards taller and finer
than the self-fertilised. In the two other pots the seedlings on both
sides were for a time exactly equal; but when the self-fertilised plants
were about 10 inches in height, they surpassed their antagonists by a
little, and ever afterwards showed a more decided and increasing
advantage; so that the self-fertilised plants, taken altogether, were
somewhat superior to the quasi-crossed plants. In this case, as in that
of the Origanum, if individuals which have been asexually propagated
from the same stock, and which have been long subjected to the same
conditions, are crossed, no advantage whatever is gained.
Several flowers on another plant of the same variety were fertilised
with pollen from the younger flowers on the same plant, so as to avoid
using the old and long-shed pollen from the same flower, as I thought
that this latter might be less efficient than fresh pollen.


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