dimorphous

Updated: May 11, 2025

Intermediate stages between them and the wholly twisted stems are not wanting, and a whole series of steps may easily be observed from sufficiently large cultures. But they are always relatively rare, and any lot of plants conveys the idea of a dimorphous race, the small twisted stems contrasting strongly with the tall straight ones.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

The ordinary twisted races on the other hand, are found in the wild state and have only to be isolated and cultivated to yield large numbers of twisted individuals. In nature they are able to maintain themselves during long centuries, quite as well as normal species and varieties. But they owe this quality entirely to their dimorphous character.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

Granting these conclusions, monstrosities on the one side, and dimorphous wild species on the other, constitute the most striking examples of the inheritance of latent characters. The bearing of the phenomena of dimorphism upon the principles of evolution formulated by Lamarck, and modified by his followers to constitute Neo-Lamarckianism, remains to be considered.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

In others the stems are all alike, green and crowned with a conelike spike of sporangia-bearing scales. Manifestly the dimorphous cases are to be considered as the younger ones, partly because they are obvious exceptions to the common rule, and partly because the division of labor is indicative of a higher degree of evolution.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

But only the useful will stand further test, and if they find suitable conditions will become specific or varietal characters. On this conclusion it becomes at once clear, why natural dimorphism is, as a rule, a very useful quality, while the cultivated dimorphous varieties strike us as something unnatural.

Hugo de Vries - Species and Varieties, Their Origin by Mutation

Here I might refer to the observations concerning the invisible dimorphous state of the flowers of the normal toad-flax. Individuals of the same type, when fertilized with each other, are nearly, but not absolutely, sterile. The yield of seeds of my peloric plants agrees fairly well with the harvest which I have obtained from some of the nearly sterile pairs of individuals in my former trial.

Hugo de Vries - Species and Varieties, Their Origin by Mutation