In a certain plant, tall stems (T) are dominant to short stems

The phenotype will have tall plants and short plants in ratio of 1:1.

The heterozygous tall plant has the genotype of Tt whereas the homozygous short plant has the genotype of tt. So the gametes produced by the long plant is T and t. Whereas the gametes produced by the short plant is t.

So the offsprings will have the genotype of Tt and tt. The Tt genotype has the phenotype of tall plant, and the genotype tt has the phenotype of short plant.

So the phenotype of the plants are tall and short, in ratio of 1:1.

The genotype of the plants are Tt and tt in ratio of 1:1.