Pterocarya


Pterocarya, often called wingnuts in English, are trees in the walnut family Juglandaceae. They are native to Asia. The botanic name is from Ancient Greek πτερον "wing" + κάρυον "nut".

Description

Pterocarya 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 but not the hickories in the same family.
The flowers are monoecious, in catkins. The seed catkins when mature are pendulous, 15–45 cm long, with 20–80 seeds strung along them.
The seeds are a small nut 5–10 mm across, with two wings, one each side. In some of the species, the wings are short and broad, in others longer and narrower.

Species

There are six species.
ImageScientific nameCommon NameDistribution
Pterocarya fraxinifoliaCaucasian wingnutCaucasus and Elburz mountains in southwest Asia.
Pterocarya hupehensisHubei wingnutCentral China.
Pterocarya macropteraLarge-winged wingnutWest and southwest China.
Pterocarya rhoifoliaJapanese wingnutJapan, eastern China.
Pterocarya stenopteraChinese wingnutChina, widespread.
Pterocarya tonkinensisTonkin wingnutSouthernmost China, Indo-China.

Another species from China, the wheel wingnut with similar foliage but an unusual circular wing right round the nut, previously listed as Pterocarya paliurus, has now been transferred to a new genus, as Cyclocarya paliurus.

Hybrids

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. × 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.