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Darwin, Charles, 1809-1882

"The Different Forms of Flowers on Plants of the Same Species"

(5/3. 'The Effects of Cross and Self-
fertilisation in the Vegetable Kingdom' 1876.) None of the nineteen illegitimate
plants in the first four classes were completely fertile; one, however, was
nearly so, yielding 96 per cent of the proper number of seeds. From this high
degree of fertility we have many descending gradations, till we reach an
absolute zero, when the plants, though bearing many flowers, did not produce,
during successive years, a single seed or even seed-capsule. Some of the most
sterile plants did not even yield a single seed when legitimately fertilised
with pollen from legitimate plants. There is good reason to believe that the
first seven plants in Class 1 and 2 were the offspring of a long-styled plant
fertilised with pollen from its own-form shortest stamens, and these plants were
the most sterile of all. The remaining plants in Class 1 and 2 were almost
certainly the product of pollen from the mid-length stamens, and although very
sterile, they were less so than the first set. None of the plants in the first
four classes attained their full and proper stature; the first seven, which were
the most sterile of all (as already stated), were by far the most dwarfed,
several of them never reaching to half their proper height. These same plants
did not flower at so early an age, or at so early a period in the season, as
they ought to have done.


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