Mendel also carried out a series of experiments in which several differentiating characters are associated. In the first experiment the parental plants (varieties) differed in the form of the seed and in the color of the albumen. The two characters of the seed plant are designated by the capital letters A and B; and of the pollen plant by small a and b. The hybrids will be, of course, combinations of these, although only certain characters may dominate. Thus in the experiments, the parents are AB (seed plant) and ab (pollen plant), with the following seed characters:—
| Seed parent | {A form round | Pollen parent | {a form angular |
| AB | {B albumen yellow | ab | {b albumen green |
When these two forms were crossed the seeds appeared round and yellow like those of the parent, AB, i.e. these two characters dominated in the hybrid.
The seeds were sown, and in turn yielded plants which when self-fertilized gave four kinds of seeds (which frequently all appeared in the same pod). Thus 556 seeds were produced by 15 plants, having the following characters:—
AB 315 round and yellow
Ab 101 angular and yellow
aB 108 round and green
ab 32 angular and green
These figures stand almost in the relation of 9 : 3 : 3 : 1.
These seeds were sown again in the following year and gave:—