Mendel’s first generation (or “P” generation) of his experiment involved crossing purebred plants with different traits, such as tall and dwarf. The resulting offspring (or “F1” generation) were all tall and had a dominant trait. In the second generation (or “F2” generation), the offspring of the F1 generation were crossed with one another. This resulted in a 3:1 ratio of tall to dwarf plants, thus showing that the trait for dwarfism was recessive. This indicates that the gene for tallness is dominant and the gene for dwarfism is recessive.