Pterocarya fraxinifolia

Pterocarya fraxinifolia, the Caucasian wingnut or Caucasian walnut, is a tree of the Juglandaceae family native to the Caucasus region, including Armenia, Azerbaijan, Georgia, Iran, Russia, Ukraine and Turkey. It was introduced to France in 1784 and to Great Britain after 1800. The tree is monoecious and grows to under 30 m, with a short, thick trunk carrying widely spreading branches that form a rounded crown, not unlike a wych elm. Its pinnate leaves can exceed 60 cm in length, with 7 to 27 stalkless leaflets, and it flowers in April, with thick green male catkins and longer, looser female catkins whose red styles become fruiting catkins 30 to 50 cm long carrying green, winged nuts. It grows fast, does best on flat ground or gentle slopes beside rivers in deep, moist soil, and usually grows in mixed stands. Fossils have been described from the early Pliocene flora of Kızılcahamam in Turkey.