I've got a rose of Sharon shrub that is well over 30 years old. Most of the shrub has pink flowers with maroon-red in the throat of the flower, a typical rose of Sharon. But right in the middle of the shrub, a large branch always gets pure white flowers year after year, no red color in the middle pure white!
At first I thought I had 2 plants that grew so close and intertwined, but they share one stem that just branched off after so many years.
Could it be a grafted branch that just didn't flourish like the branches that produced pink flowers, or could it be genetic where a single branch produced mutants that lack pigment, the branch has never been pruned or removed.
I saved seeds and most come out pink, but some do produce the pure white flowers.