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Darwin, Charles, 1809-1882

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


26 : Mid-styled : 86.0 : 109 : 61 : 66.
27 : Mid-styled : 99.4 : 122 : 53 : 76.
28 : Mid-styled : 89.0 : 119 : 69 : 68.
29 : Long-styled : 100.0 : 121 : 77 : 107.
30 : Long-styled : 94.0 : 106 : 66 : 101.
31 : Long-styled : 90.6 : 97 : 79 : 98.
CLASS 7. ILLEGITIMATE PLANTS RAISED FROM MID-STYLED PARENTS FERTILISED WITH
POLLEN FROM THE LONGEST STAMENS OF THE SHORT-STYLED FORM.
32 : Mid-styled : 127.2 : 144 : 96 : 98.
33 : Short-styled : 113.9 : 137 : 90 : 137.
The lessened fertility of most of these illegitimate plants is in many respects
a highly remarkable phenomenon. Thirty-three plants in the seven classes were
subjected to various trials, and the seeds carefully counted. Some of them were
artificially fertilised, but the far greater number were freely fertilised (and
this is the better and natural plan) through the agency of insects, by other
illegitimate plants. In the right hand, or percentage column, in Table 5.30, a
wide difference in fertility between the plants in the first four and the last
three classes may be perceived. In the first four classes the plants are
descended from the three forms illegitimately fertilised with pollen taken from
the same form, but only rarely from the same plant. It is necessary to observe
this latter circumstance; for, as I have elsewhere shown, most plants, when
fertilised with their own pollen, or that from the same plant, are in some
degree sterile, and the seedlings raised from such unions are likewise in some
degree sterile, dwarfed, and feeble.


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