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Updated: June 14, 2025
This form is met with in different parts of France, while the biennis and muricata are very common in the sandy regions of Holland, where I have observed them for more than 40 years. They are very constant and have proven so in my experiments. Besides these three species, the large-flowered evening-primrose, or Oenothera lamarckiana, is found in some localities in Holland and elsewhere.
Rubrinervis is a mutation from Lamarckiana, chiefly distinguished by red midribs in the leaves and red stripes on the sepals. When propagated from self-fertilised seed it produced about 95 per cent. of offspring with the same characters, and the remaining 5 per cent. mutants, one of which was laevifolia which had been found by De Vries among plants growing wild at Hilversum.
This latter hypothesis, already proposed by various authors, notably by Bateson in a remarkable book, has become deeply significant and acquired great force since the striking experiments of Hugo de Vries. This botanist, working on the OEnothera Lamarckiana, obtained at the end of a few generations a certain number of new species.
Both are true elementary species, differentiated from lamarckiana in nearly all their organs and qualities, but not showing any preponderating character of a retrograde nature. Their differences may be compared with those of the elementary species of other genera, as for instance, of Draba, or of violets, as will be seen by their description.
But whether, besides this, similar strains are produced anew by the old lamarckiana group, it is impossible to decide on the sole ground of these field-observations. The same holds good with the other novelties.
Attempts, however, to produce it by crossing of other forms have not succeeded, and a specimen has been discovered at the Museum d'Histoire Naturelle at Paris, collected by Michaux in North America about 1796, which agrees exactly with the Oenothera Lamarckiana naturalised or cultivated in Europe.
Both the giant and the red-veined species are easily recognized in the rosette-stage. Even the very young seedlings of the latter are clearly differentiated from the lamarckiana, but often a dozen leaves are required, before the difference may be seen.
But besides these a rubrinervis made its appearance and flowered the following year. This fact at once revealed the possibility that the instability of lamarckiana might not be restricted to the three new types now under observation. Hence the question arose how it would be possible to obtain other types or to find them if they were present.
All organs and all qualities of lamarckiana fluctuate and vary in a more or less evident manner, and those which I had the opportunity of examining more closely were found to comply with the general laws of fluctuation. But such oscillating changes have nothing in common with the mutations.
Instead of giving an exhaustive survey of hybrids, I simply cite my crosses between lamarckiana and biennis, as having nearly the aspect of the last named species, and remaining true to this in the second generation without any sign of reversion or of splitting.
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