Pterocarya fraxinifolia

The wingnuts (Pterocarya) are large deciduous monoecious trees (i.e. male and female flowers in the same tree) whose dangling inflorescences develop into fruit catkins up to half a metre long. The name comes from the decorative winged nuts. This particular species, the Caucasian wingnut, has grown in earlier periods of warmer climate in Europe but has had to retreat to its present habitat in the river valleys around the Caspian Sea. It was taken into cultivation in western Europe at the end of the 1700s.