Flower forest biome only generates poppies, rose bushes, peonies, and lilacs

There are only poppies, rose bushes, peonies, and lilacs in flower forest.

Steps to Reproduce:

1. Create a new world
2. Locate a flower forest biome

Observed Results:
Only poppies, rose bushes, peonies, and lilacs generate.

Expected Results:
Various other flowers should also generate.