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Updated: June 9, 2025
Its immediate predecessor must have been the subgenus Onagra, which is considered by some authors as consisting of a single systematic species, Oenothera biennis. Its multifarious forms point to a common origin, not only morphologically but also historically.
The question to be considered here is how far the claim is justified that the facts of this kind hitherto discovered afford an explanation of the process of evolution. It seems probable that mutations are of different kinds, as exemplified in Oenothera by gigas and rubricalyx respectively, the former producing only sterile hybrids, the latter behaving exactly like a Mendelian unit.
Hence there can be little doubt that the unpaired units are the cause of this decrease in reproductive power. The genus Oenothera is to a large degree devoid of varietal characteristics, especially in the subgenus Onagra, to which biennis, muricata, lamarckiana and some others belong.
The difference was small, but constant on all the flowers, each single plant clearly belonging to one or the other of the two types. Probably two elementary species were intermixed here, but whether one is the systematic type and the other a mutation, remains to be seen. Nor seem these two types to exhaust the range of variability of Oenothera cruciata. Dr.
The other head comprises two fertile forms, O. scintillans and O. elliptica, which may easily be fertilized with their own pollen, but which gave a progeny only partly similar to the parents. The Oenothera lata is a very distinct form which was found more than once in the field, and recently in a luxuriant flowering specimen.
So Lamarck unconsciously discovered and described himself the plant, which after a century, was to become the means of an empirical demonstration of his far-reaching views on the common origin of all living beings. Oenothera lamarckiana is considered in Europe as a garden-plant, much prized for parks and ornamental planting. It is cultivated by seed-merchants and offered for sale.
Thus the factor that causes rudimentary wings also produces sterility in females, general loss of vigour, and short hind legs. The facts to which I shall refer concerning Oenothera are for the most part quoted on the authority of Dr. The occurrence of mutations in Oenothera was first noticed by De Vries, the Dutch botanist, in the neighbourhood of Amsterdam in 1886.
He has not only studied the chromosomes in the gametes of this fly, and made Mendelian crosses with it, but has obtained numerous mutations, so that his work is a very important contribution to the mutation doctrine. Drosophila in the hands of Professor Morgan and his students and colleagues has thus become as classical a type as Oenothera in those of the botanical mutationists.
It is quite obvious that Oenothera lamarckiana was in a mutating condition when I first saw it, seventeen years ago. How long had it been so? Had it commenced to mutate after its introduction into Europe, some time ago, or was it already previously in this state? It is as yet impossible to decide this point.
No occurrence of possible varietal characteristics obscures the result, and in this respect this hybrid stands out much more clearly than all those between garden-plants, where varietal marks nearly always play a most important part. From the breeder's point of view our hybrid Oenothera would be a distinct gain, were it not for the difficulty of its propagation.
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