Through Darwin's patient study of this trimorphic flower, it has assumed so important a place in his theory of the origin of species that its fertilization by insects deserves special attention.
Leggett, who made a careful study of the flower, tells that three forms occur, not on the same, but on different plants, being even more distinctly trimorphic than the purple Loosestrife.
So it was with 56 seedlings from the long-styled form of the trimorphic Lythrum salicaria, and with numerous seedlings from the long-styled form of Oxalis rosea.
We shall, perhaps, best perceive the complex and extraordinary nature of the marriage arrangements of a trimorphic plant by the following illustration.
With dimorphic species two illegitimate unions, and withtrimorphic species twelve are possible.
We thus see that the organs in these two forms differ from one another and are arranged in an analogous manner, as in the long and short-styled forms of the trimorphic species of Lythrum and Oxalis.
I will begin with trimorphic plants, and I must remind the reader that each of the three forms can be fertilised in six different ways; so that all three together can be fertilised in eighteen different ways.
Moreover, trimorphicplants evidently come under the same category with dimorphic, and the former cannot be looked at as tending to become dioecious.
Hildebrand possessed in a living state only the long-styled form of this trimorphic Chilian species.
I hear from him that this is the case with the heterostyled trimorphic O.
I hope also to republish a revised edition of my book on Orchids, and hereafter my papers on dimorphic and trimorphic plants, together with some additional observations on allied points which I never have had time to arrange.
In the very different case of trimorphic heterostyled plants, the two sets of stamens in the same flower have widely different fertilising powers.
The ovules of a heterostyled trimorphic plant are affected very differently by pollen from the three sets of stamens belonging to the same species.
I have described in my paper 'On the Illegitimate Unions of Dimorphic and Trimorphic Plants' this remarkable variety, which was sent to me from Edinburgh by Mr. J.
These latter plants cannot fail to act on each other like dimorphic or trimorphic species, in which the union of two individuals is necessary for full and normal fertility.
My observations 'On the Character and hybrid-like nature of the offspring from the illegitimate union of Dimorphic and Trimorphic Plants' were published in the 'Journal of the Linnean Soc.
After arriving at these conclusions, I was led to investigate a subject which throws considerable light on hybridism, namely, the fertility of heterostyled or dimorphic and trimorphic plants, when illegitimately united.
This appears all the more probable, if we admit that the structural differences between the forms of dimorphic andtrimorphic plants, as the length and curvature of the pistil, etc.
With trimorphic species six unions are legitimate, or fully fertile, and twelve are illegitimate, or more or less infertile.
We shall clearly understand why monoecious and dioecious,--why dichogamous, dimorphic and trimorphicplants exist, and many other such cases.
Dimorphic and trimorphic plants, though they are hermaphrodites, must be reciprocally crossed, one set of forms by the other, in order to be fully fertile, and in some cases to be fertile in any degree.
Lythrum and the trimorphic Oxalis are the most wonderful cases.
All dimorphic and trimorphic plants present such difference in function and in size.
If you can find a dimorphic Oxalis it will be a new point, for all known species are trimorphic or monomorphic.
The case described in your last letter of the trimorphic monocotyledon Pontederia is grand.
It is possible to raise from dimorphic species, both long-styled and short-styled illegitimate plants, and from trimorphic plants all three illegitimate forms.
No one until lately would have imagined that in dimorphic and trimorphic plants the different lengths of the stamens and pistils, and their arrangement, could have been of any service, but now we know this to be the case.
So it is with the reciprocally dimorphic and trimorphic plants previously alluded to.
To Sprengel, and specially to Darwin, physiologists are indebted for the demonstration of the relation of di- and trimorphic flowers to fertilisation.
During the same year I published in the Journal of the Linnean Society, a paper On the Two Forms, or Dimorphic Condition of Primula, and during the next five years, five other papers on dimorphic and trimorphic plants.
This appears all the more probable, if we admit that the structural differences between the forms of dimorphic and trimorphic plants, as the length and curvature of the pistil, &c.
The case is closely analous with dimorphic and trimorphic plants, which can be fully fertilised only by plants belong to the opposite form, and not, as in the foregoing cases, in differently by any other plant.
We shall clearly understand why monoecious and dioecious,--why dimorphic and trimorphic plants exist, and many other such cases.
With trimorphic species six unions are legitimate or fully fertile, and twelve are illegitimate or more or less infertile.
If Natural Selection could not accumulate varying degrees of sterility for the plant's benefit, then how did sterility ever come to be associated with one cross of a trimorphic plant rather than another?
The above list will hopefully give you a few useful examples demonstrating the appropriate usage of "trimorphic" in a variety of sentences. We hope that you will now be able to make sentences using this word.
