Walnut trees are any species of tree in the plant genus Juglans, the type genus of the family Juglandaceae, the seeds of which are referred to as walnuts. All species are deciduous trees, 10–40 metres (33–131 ft) tall, with pinnate leaves 200–900 millimetres (7.9–35.4 in), 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.
The 21 species in the genus range across the north temperate Old World from southeast Europe east to Japan, and more widely in the New World from southeast Canada west to California and south to Argentina.
Edible walnuts, which are consumed worldwide, are usually harvested from cultivated varieties of the species Juglans regia. China produces half of the world total of walnuts.
Etymology
The common name walnut derives from Old English wealhhnutu, literally 'foreign nut' (from wealh 'foreign' + hnutu 'nut'), because it was introduced from Gaul and Italy. The Latin name for the walnut was nux Gallica, "Gallic nut". The name Juglans was apparently conjured by Linnaeus himself, replacing the prior Nux, by combining Ju from Jupiter with the Latin glans meaning 'acorn', referring to the association of the plant with Jupiter by the Romans.
Folklore
Tradition has it that a walnut tree should be beaten. This would have the benefit of removing dead wood and stimulating shoot formation.
