Mass Mutations and Twin Hybrids of Oenothera Grandiflora Ait.

Abstract

1. Oenothera grandiflora Aiton from Castleberry, Alabama, splits in my cultures in every generation into two types. One of them consists of strong, green plants of the parent type; the other of weak, yellow individuals, of which only a few are vigorous enough to flower and ripen their seeds. This weak type is called O. grandiflora mut. ochracea. 2. Besides these it produces other mutants in the ordinary proportions of 0. 1-1 per cent, namely, mut. lorea with almost linear leaves and mut. gigas with 28 chromosomes and the corresponding stoutness of all its organs. These two types are constant from seed, but the gigas keeps on mutating into lorea and ochracea. 3. The crosses among O. grandiflora, O. ochracea, and O. lorea show that these forms are isogamic, the pollen carrying the same hereditary qualities as the egg cells. 4. O. grandiflora yields twin hybrids with the same species which produce twins in their combinations with O. Lamarckiana. The female organs of O. biennis, O. syrticola (muricata), O. su...