Thorhalla *seems* to be taking pollen from tetraploid parents. I will try to confirm this as time goes on, but I spent the beginning of last season thinking Thorhalla was tet and pollinated with tet pollen, only to realize my mistake, but still end up with seeds. (So far, I got seeds from Thorhalla that had pollen parents Duck's Dark Side and from Aerial Applique.) I'll only know for sure if/when the seedlings grow out and I can see if the seedlings resemble their supposed pollen parents.

If anyone else has Thorhalla and wants to run some tet crossing experiments, please let me know how it turns out for you!