This experiment involved 2 characteristics in which he cross (breed) the plants. He had a dominant and recessive, which basically when the dominant plant takes over the recessive plant and makes more of itself. Alleles are genes that come from the plants to make another plant. If the plant makes the same allele then it is considered homozygous, but if it makes two different alleles then it is heterozygous.
MENDEL'S SECOND EXPERIMENT!!! PLANT REPRODUCTION!!!
Once the plant is in the reproduction stage where it can make another plant then that's when genotype and phenotype come in. Genotype determines phenotype. Your phenotype are the physical things outside the body and the genotype are the type of genes inside the body to make your traits.