Pistachio, small tree of the cashew family (Anacardiaceae) and its edible seeds, grown in dry lands in warm or temperate climates. The pistachio tree is believed to be indigenous to Iran. It is widely cultivated from Afghanistan to the Mediterranean region and in California. The seed kernels can be eaten fresh or roasted and are commonly used in a variety of desserts, including baklava, halvah, and ice cream. They are also used for yellowish green coloring in confections. The seeds are high in protein, fat, dietary fibre, and vitamin B6.