| → both with 1866 1869 |
| the two having 1872 |
|
| → there are 1866 1869 |
| the three forms possess 1872 |
|
| → in any 1866 1869 |
| half the stamens in 1872 |
|
| → half the stamens in each 1866 1869 |
| OMIT 1872 |
|
| Reciprocal
Dimorphism
and
Trimorphism
. |
| This subject may be here briefly discussed, and will be found to throw
light on hybridism. Several plants belonging to distinct orders present two forms,
in about equal
differ in no respect except in their reproductive organs; one form having a long pistil with short stamens, the other a short pistil with long stamens;
→both with
differently sized pollen-grains. With trimorphic plants there are three forms likewise differing in the lengths of their pistils and stamens, in the size and colour of the pollen-grains, and in some other respects; and as in each of the three forms there are two sets of stamens,
→there are
altogether six sets of stamens and three kinds of pistils. These organs are so proportioned in length to each other,
→in any
two of the
→half the stamens in each
stand on a level with the stigma of the third form. Now I have shown, and the result has been confirmed by other observers, that, in order to obtain full fertility with these plants, it is necessary that the stigma of the one form should be fertilised by pollen taken
the stamens of corresponding height in
form. So that with dimorphic species two unions, which may be called legitimate, are fully
and two, which may be called illegitimate, are more or less infertile. With trimorphic species six unions are legitimate or fully fertile, and twelve are illegitimate or more or less infertile. |
|
| The infertility which may be observed in various dimorphic and trimorphic plants, when they are illegitimately fertilised, that is by pollen taken from stamens not corresponding in height with the pistil, differs much in degree, up to absolute and utter sterility; just in the same manner as occurs in crossing distinct species. As
|
