These genes influence the overall size of the plant.

The sp or self-pruning gene is what makes a variety determinate, by influencing the hormones in the growing tips so that it’s more flowers than vegetative growth, and they eventually peter out.

The br or brachtyic gene results in shortened internodes (spaces between sets of leaves) so that the plant is more compact.

The d or dwarf gene results in all parts of the plant being smaller by about half.

When combined, the genes have an effect of creating especially small or “micro-dwarf” plants, that can be about 8-10 inches tall.

Flavor is often compromised in determinate and micro-dwarf (less so in brachytic and standard dwarf), because of the lowered ratio of leaves to fruit (a factor in creating sugars and flavor), but there are passionate folks searching for ways to maximize their output, by breeding with high sugar varieties like Sweet Aperitif (Solanum pimpinellifolium parentage), and varieties that have the Intense pigment gene.