Further regarding Whitestone:  I have attached five pictures:  Whitestone itself (in case you are not familiar with it), Whitestone open pollinated, Whitestone x (Dumper Yellow x Phipps 32), Whitestone x yakushimanum (not my cross) and Whitestone x Dexter’s Spice.  Note the mauve color of Whitestone x Dexter’s Spice.  I am assuming that the mauve color is coming from Whitestone as Dexter didn’t use catawbiense in his hybridizing.  Of course, he could have used a hybrid that had it in its background.

Whitestone

Whitestone open pollenated

Whiteston x (Dumper Yellow x Phipps 32)

Whitestone x yakushimanum

Whitestone x Dexter Spice