3 years ago I planted a row of 5 "Mop-head" Catalpas. This year one of the trees has sprouted beautiful white flowers with a yellow "eye" - similar looking to a white iris. I have never heard of or seen a flowering Mop-head Catalpa. And just the one tree has flowers. My mother-in-law has had a row of these trees in her backyard for over 25 years and has never seen them flower either. Also, how does just one tree pollinate, if indeed Mop-heads flower? Thanks!
Catalpa bignonioides 'Nana'. Maybe the one has reverted to the type or the stock has sent up a sprout that has grown through the 'Nana' part and started to flower.