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Darwin, Charles, 1809-1882

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

They have a
rather complicated structure, and appear to be adapted for
cross-fertilisation, but were not carefully examined by me. They are not
easy to fertilise artificially, and it is possible that some of the
flowers which I thought that I had succeeded in crossing were afterwards
spontaneously self-fertilised under the net. Sixteen capsules from the
crossed perfect flowers contained on an average ninety-three seeds (with
a maximum in one capsule of 137), and thirteen capsules from the
self-fertilised perfect flowers contained sixty-two seeds (with a
maximum in one capsule of 135); or as 100 to 67. But I suspect that this
considerable excess was accidental, as on one occasion nine crossed
capsules were compared with seven self-fertilised capsules (both
included in the above number), and they contained almost exactly the
same average number of seed. I may add that fifteen capsules from
self-fertilised cleistogene flowers contained on an average sixty-four
seeds, with a maximum in one of eighty-seven.
Crossed and self-fertilised seeds from the perfect flowers, and other
seeds from the self-fertilised cleistogene flowers, were sown in five
pots, each divided superficially into three compartments. The seedlings
were thinned at an early age, so that twenty plants were left in each of
the three divisions. The crossed plants when in full flower averaged 4.3
inches, and the self-fertilised plants from the perfect flowers 4.


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