The pecan is in fact a tree nut and it comes from the hickory species. It is native to the Mexican and South-Central North American area. The tree that pecans grow on are classified as being deciduous and can grow up to 130 feet tall, though they rarely reach heights of over 140 feet.
The pecan is actually not technically a nut but rather a drupe which is a fruit that has a single stone or pit and is encompassed in a husk. These nuts tend to be a dark brown color with an oval or oblong shape. The outer husk of the pecan is around 0.16 inches thick and begins green, turning brown over time as it begins to mature.