Wingnut trees (pterocarya)
What is your experience of wingnut trees? Around here the Caucasian wingnut pterocarya fraxinifolia is by far most common and has good hardiness. But there are also a few asian species and now I have come by p. stenoptera and p. hupehensis and can also buy p. rhoifolia. What hardiness can be expected for these? And over all, what differences is there between these four species?