Tree nuts are a type of seed that is enclosed in a hard shell. The hard shell provides the kernel, or nut, with adequate protection from winter's and nature's elements. Due to their high fat content and unique flavor, many tree nut seeds have become a commonly accepted household staple for snacking and cooking.
Determine the location where the nut tree was grown. If the area has harsh winters with large amounts of snow and extremely cold temperatures, then the nut is most likely a walnut, chestnut or pecan, as these trees require a cold-snap for excellent production. If the climate is mild with moderate winter temperatures, then it is most likely a pistachio. If the tree is located in a tropical climate with no winter whatsoever, then it is most likely a cashew.
Look at the tree's leaf shape. If the tree's leaves are large with a three prongs, then it is a maple tree. If the tree's leaves are round to semi-ovular then it is most likely a pecan tree. If the tree's leaves are bright green and the tree itself is short, then it is a cashew tree. If the tree's leaves are ovular and slightly curled then it is either a pistachio or chestnut tree.
Look at the seed itself. If the seed is small and green, then it is a pistachio. If the seed is round with a root at the tip then it is a chestnut. If the seed has a crescent shape then it is a cashew. If the seed is ovular and tan colored then it is a pecan. If the seed is ovular and black then it is a walnut.