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 Japanese Wingnut (Pterocarya rhoifolia)
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The wingnuts are plants in the genus Pterocarya (from Ancient Greek pteron, "wing" + karyon, "nut") in the walnut family Juglandaceae, native to Asia.
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Description
They are deciduous trees, 10-40m tall, with pinnate leaves 20-45cm 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.
The flowers are monoecious, in catkins. The seed catkins when mature (about 6 months after pollination) 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 (5-10 mm) and broad (5-10 mm), in others longer (10-25 mm) and narrower (2-5 mm).
Species
There are six species of wingnut.
- 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.
Uses
Wingnuts are very attractive, large and fast-growing trees, occasionally planted in parks and large gardens. The commonest in general cultivation outside of 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.
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