The seed of the fruit of a small evergreen tree. Two colors -red and green- usually are associated with pistachio nuts. The thin, oval shell, which is split at one end, is naturally beige, but often is dried bright red. Inside, the pistachio, which is usually about 1/2 inch long, has a paper-thin brown skin and a distinctive green to yellow flesh. Pistachios have a mildly sweet flavor similar to almonds. These nuts are added to sauces, stuffing, pates, pastries, and ice cream and are used widely in Mediterranean and Asian cuisines. They are an excellent source of potassium, magnesium, and copper. The fat content of the pistachio is composed of 83% unsaturated fatty acids. The Greek island of Aegina produces some of the world’s finest pistachios.