Vietnam or Thailand ? Vote for the TOP Country of the Week !
Updated: June 2, 2025
Both of the pure groups have therefore reappeared in the same numbers. Calling A the specimens with the pure active mark, L those with the latent mark, and H the hybrids, these proportions may be expressed as follows: 1A+2H+1L. This simple law for the constitution of the second generation of varietal hybrids with a single differentiating mark in their parents is called the law of Mendel.
Bailey says, "Of all those which have more points of resemblance than of difference," and a description of the variety is of that ideal which in common practice is not fixed, but may and generally does vary not only with different people but from time to time. The only foundation for varietal names in plants of this class is an agreement as to the ideal the name shall stand for.
In unbalanced crosses of the genus Oenothera the hybrids of such reciprocal unions are often different, as we have previously shown. Sometimes both resemble the pollen parent more, in other instances the pistil-parent. In varietal crosses no such divergence is as yet known.
Whenever such sports were worked up, a few years sufficed to reach the entire development of the new varietal attribute. From this superficial survey of historical facts, the inference is forced upon us that the chance of producing a new double variety is good enough to justify the attempt.
Briefly considering the different forms, we may state that the full experimental proof has been given for the origin of gigas and rubrinervis, for albida and oblonga, and even for nanella, which is to be considered as of a varietal nature; with lata the decisive experiment is excluded by its unisexuality. laevifolia and brevistylis were found originally in the field, and never appeared in my cultures.
All of these three rules are supported by a large amount of evidence. The complete fertility of varietal hybrids is so universally acknowledged that it is not worth while to give special instances. With many prominent systematists it has become a test between species and varieties, and from our present point of view this assumption is correct.
There are a large number of cultivated varieties of different species which by some peculiarity do not seem adapted for the conditions of life in the wild state. These last have often been used to prove the origin of varietal forms during culture. One of the oldest instances is the variety or rather subspecies of the opium-poppy, which lacks the ability to burst open its capsules.
Phyllonoma ruscifolia, a saxifragaceous plant, bears the same specific name, indicating a similar origin of the flowers. Other instances have been collected by Casimir de Candolle, but their number is very small. As a varietal mark, flowers on leaves likewise rarely occur.
Even if a complete, exact and reliable description of a variety was published by disinterested persons, one could not be sure of getting seed from seedsmen which would produce plants of that exact type, since there is no agreement or uniformity among them as to the exact type any varietal name shall stand for.
One is the visible quality of the individuals and the other is the direct observation of the degree in which the attribute is transmitted. These are by no means parallel, and seem in some sense to be nearly independent of each other. The fact that the worst atavists may have the highest percentage of varietal units seems to leave no room for another explanation.
Word Of The Day
Others Looking