Johann gregor mendel's work in genetics focused on traits that exhibit discontinuous variation. what kind of traits are these?

Discontinuous variation is when a trait is seen in a population in two or more different forms and there is no continuation along a gradient. A good example that Mendel studied is flower color. The flowers  were either white or purple. There was no in between color. This is caused by an allele for purple or a lack of an allele for purple, which produces no pigment, or  white. 

They get pregnant at younger ages