For this example we will also be breeding two flowers together. The genotypes of these flowers will be homozygous instead of heterozygous, meaning the genes of the genotype will be exactly the same. The dominant gene or R will affect the flower's phenotype by making it red, while the recessive gene will affect the phenotype by making the flower white.
How this Homozygous Punnett Square Works
In this homozygous Punnett square we are combining two homozygous genotypes together. One parent is homozygous dominant and one parent is homozygous recessive. When you use the Punnett square method you will get a combination of these genotypes, resulting in a all heterozygous offspring.
Source: http://dvbiology.org/biologyweb/bgene.htm
Genotypes and Phenotypes
For the genotypes for the offspring are 100% Rr, meaning all offspring are heterozygous. The phenotypes of this offspring are 100% red, this is from the dominant gene R being present in all genotypes.