The phenotype of the heterozygous pea plant with violet flowers is Vv (V for dominant violet allele and v for recessive white allele). The phenotype of the homozygous pea plant with white flowers is vv. This is a monohybrid cross.

When we create a Punnett square for this cross, we have :

$$ \begin{array}{|l|l|l|} \hline & \mathbf{V} & \mathbf{v} \ \hline \mathbf{v} & \operatorname{Vv} \text { (violet) } & \text { vv (white) } \ \hline \mathbf{v} & \operatorname{Vv} \text { (violet) } & \text { vv (white) } \ \hline \end{array}