Pterocarya

Pterocarya, often called wingnuts in English, are trees in the walnut family Juglandaceae. They are native to Asia and the extreme southeast of Europe, from the Caucasus Mountains east to Japan. The botanic name is from Ancient Greek πτερόν (pteron) "wing" + κάρυον (karyon) "nut". The genus is of particular scientific interest as a classic relict lineage, with a modern distribution disjunct between East Asia and the Caucasus–West Asian region, while its fossil record shows it was once widespread across much of the Northern Hemisphere. In Western Europe, the genus was present on Doggerland until shortly before it was flooded a few thousand years ago. Many fossils are known from the New World and the genus survived in the New world till the Pliocene. Most species of wingnuts are large, fast-growing trees, often associated with riverbanks, floodplains, and moist temperate forests. They are distinguished by pinnate leaves, monoecious flowers, and fruit with lateral wings that aid wind and water dispersal. Several species, such as Pterocarya stenoptera and Pterocarya fraxinifolia, are widely cultivated as ornamental or shade trees due to their graceful form and tolerance of wet soils.