Don't know for sure so I guess I'm spreading a rumor. H. Diana is a hybrid of Hibiscus syriacus X Hibiscus rosa-sinensis. Thus why it is sterile and can't produce seed. However I don't believe it.
Since I don't own a 'Diana' I can't check out the flower to see what parts are missing for reproduction.
It is reported to have a larger flower than regular rose of sharon. Can I have help on this Susan?
Check out your flowers and size this summer for us.
