Pistachios -
Pistachios have a distinctive green color to the nut. Pistachios grow on the trees in clusters similar to grapes. When conditions are favorable, the pistachio shell splits open...prior to harvesting. Whereas the almond tree requires honey bees for pollination, pistachio trees rely on wind. Male trees are planted in the orchards to take advantage of prevailing winds, which carry the pollen from the male to the female flowers. Pistachio trees begin production in about six or seven years, but do not produce a full crop until the fifteenth to twentieth year. Under favorable conditions, however, pistachio trees live and produce nuts for centuries. A 700 year old tree was still standing in Iran as of 1984.

Almonds -
The Almond tree is a native to the warmer parts of western Asia and of North Africa, but it has been extensively distributed over the warm temperate region of the Old World, and is cultivated in all the countries bordering on the Mediterranean. It was very early introduced into England, probably by the Romans, and occurs in the Anglo-Saxon lists of plants, but was not cultivated in England before 1562, and then chiefly for its blossom. The Almond, Prunus dulcis, is a graceful, medium sized tree of the rose family.
Keep reading at http://www.botanical.com/botanical/mgmh/a/almon026.html

Cashews -
This name itself means "shaped like a heart", which is the general shape of a cashew nut shell. The cashew nut is the true fruit from the tree, while the apple is the swollen stalk supporting the flower. The nut shell is smooth, oily and about one-eighth of an inch thick. Find out more at: http://www.botanical.com/botanical/mgmh/c/casnut29.html