The genetics ofverbena. I

Summary

• 1. The garden forms of “Verbena hybricla” show variations of two kinds, the first apparently derived from differences between its four reputed parental species, the second -from mutations which have taken place since the original hybridization about a hundred years ago.

• 2. The second group depends on ten gene differences, which show complete dominance of a common wild type. The first group on the other hand depends on eight gene differences which show various degrees of dominance.

• 3. There are two sets of triple allelomorphs controlling colour, which are remarkable in that the extreme members of each series determine the same phenotype and differ only in that one is dominant, the other recessive. to the intermediate allelomorph. Possibly the dominant member is derived from a species difference, the recessive from mutation.

• 4. Aberrant ratios, modifying factors and extremely close linkages occur with exceptional frequency and are probably due to the hybrid origin of the group.

The pigment chemistry will be described later. I would be most grateful if collectors or others in South America would supply seeds from the wild of any species mentioned in this paper, or any other closely related species.