|Japanese Wingnut (Pterocarya rhoifolia)|
Nutt. ex Moq.
They are deciduous trees, 10–40 m tall, with pinnate leaves 20–45 cm long, with 11–25 leaflets; the shoots have chambered pith, a character shared with the walnuts (Juglans) but not the hickories (Carya) in the same family.
There are six species.
- Pterocarya fraxinifolia - Caucasian Wingnut. Caucasus and Elburz mountains in southwest Asia.
- Pterocarya hupehensis - Hubei Wingnut. Central China.
- Pterocarya macroptera - Large-winged Wingnut. West and southwest China.
- Pterocarya rhoifolia - Japanese Wingnut. Japan, eastern China (Shandong).
- Pterocarya stenoptera - Chinese Wingnut. China, widespread.
- Pterocarya tonkinensis - Tonkin Wingnut. Southernmost China (Yunnan), Indo-China.
Another species from China, the Wheel Wingnut with similar foliage but an unusual circular wing right round the nut (instead of two wings at the sides), previously listed as Pterocarya paliurus, has now been transferred to a new genus, as Cyclocarya paliurus.
Wingnuts are very attractive, large and fast-growing trees, occasionally planted in parks and large gardens. The most common in general cultivation outside Asia is P. fraxinifolia, but the most attractive is probably P. rhoifolia. The hybrid P. x rehderiana, a cross between P. fraxinifolia and P. stenoptera, is even faster-growing and has occasionally been planted for timber production. The wood is of good quality, similar to walnut, though not quite so dense and strong.