Walnut
(This article is about the walnut tree. For other uses see Walnut (disambiguation).)
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The Walnut is any tree of the genus Juglans which belong to the walnut family, or Juglandaceae. They are deciduous trees, 10-40m tall, with pinnate leaves 20-90cm long, with 5-25 leaflets; the shoots have chambered pith, a character shared with the wingnuts (Pterocarya) but not the hickories (Carya) in the same family.
Probably the two best-known members of the genus are the Persian or Common walnut Juglans regia, native from the Balkans in southeast Europe, southwest & central Asia to the Himalaya and southwest China, and also often but incorrectly known as "English walnut" in the United States (the species is not native to England), and the Black walnut Juglans nigra in eastern North America.
These two species are important for their attractive timber. Walnut hulls are used as a dye source, yielding a rich yellow-brown color.
The nuts of all the species named above, as well as other species, are edible, but the walnuts commonly available in stores are the Persian walnut. A horticultural variety selected for thin nut shells and hardiness in temperate zones is sometimes known as the Carpathian walnut. The nuts are rich in oil, and are widely eaten both fresh and in cookery. They need to be kept dry and refrigerated to store well; in warm conditions they become rancid in a few weeks, particularly after shelling.
