Walnut

n. large shady deciduous tree cultivated for its nuts and wood; nut of the walnut tree which is encased in a hard wrinkly round shell; wood of the walnut tree; light brown color

Walnuts (genus Juglans) are plants in the family Juglandaceae. They are deciduous trees, 10 - 40 metres tall (about 30-130 ft.), with pinnate leaves 200 - 900 millimetres long (about 7-35 inches), 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.
See more at Wikipedia.org...

Noun
1. nut of any of various walnut trees having a wrinkled two-lobed seed with a hard shell
(hypernym) edible nut
(hyponym) black walnut
(part-holonym) walnut tree
2. hard dark-brown wood of any of various walnut trees; used especially for furniture and paneling
(hypernym) wood
(substance-holonym) walnut tree
3. any of various trees of the genus Juglans
(synonym) walnut tree
(hypernym) nut tree
(hyponym) California black walnut, Juglans californica
(member-holonym) Juglans, genus Juglans

(n.)
The fruit or nut of any tree of the genus Juglans; also, the tree, and its timber. The seven or eight known species are all natives of the north temperate zone.
  

These nuts are native to Asia and grow on walnut trees inside green pods which turn brown and wood like when they dry.