Which of the following foods are technically classified as a fruit?
Considering broccoli, pistachios, celery and green beans, the answer is: pistachios.
Technically speaking, a pistachio may refer to any one of several tree species of the Pistacia genus, which is part of the same family as cashews, mango, and poison ivy. In the spring, pistachio trees develop grape-like clusters of green colored fruits, known as drupes, which gradually harden and turn red. Eventually, the fruit will harden and the shell will pop open to reveal the pistachio within.
The pistachio belongs to a group of drupes called “culinary nuts” that include cashews and almonds. For most drupes, such as peaches, cherries and apricots, we tend to eat the fruity flesh and discard the seed, yet the opposite is true of pistachios. Indeed, the fruit of the pistachio is actually its shell, which gets removed to reveal the tasty pistachio seed at its center. Conversely, a real nut, also called a “true nut” or a “botanical nut,” is a seed encased in a hard, woody shell. This group includes favorites such as hazelnuts, chestnuts and acorns.
The pistachio is native to Asia and the Middle East, where it has been cultivated for thousands of years. In the United States, pistachios were mainly imported until the 1970s, when domestic production picked up in dry, Western climates. Botanist William E. Whitehouse, a leader of the movement toward domestic pistachio production, began importing and experimentally planting pistachio trees in California the 1920s. Today, California is responsible for 99 percent of domestic production, with the other 1 percent coming out of Arizona and New Mexico. The production of pistachios has exploded over recent decades, and the United States now produces over 80 million pounds of the "nuts" per year.
Learn more about the history and cultivation of the pistachio here.