The number of stamens are equal to the number of perianth lobes in the flowers of

Calyx and Corolla together called as perianth. In pea there are 5 sepals and 5 petals. i.e. 10 perianth lobes. The number of stamens are also 10. In Mustard, the number of perianth lobes is 4 sepals and 4 petals and putting together 8. The number of stamens is 6. Perianth lobes are not equal to number of stamens. In Petunia and Makoi (Solanaceae), there are 10 perianth lobes and 5 stamens.