This year, many of the pistachios grown in California's San Joaquin Valley are missing the green, fatty meat that nut lovers crave. Instead, they're empty inside, the result of drought, heat and weather pattern changes that have messed with pistachio tree fertilization. Kreg Steppe/Flickr hide caption

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Before blight decimated most of the American chestnut trees in the U.S., one of the great autumn pastimes was collecting the nuts and transforming them into pan-fried bread, porridge, pickles, preserves or cream pie. Timothy Van Vliet/Wikipedia hide caption

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Dead almonds on a drought-stricken tree near Fresno, Calif., on April 10, 2015. Michael Nelson/EPA/Corbis hide caption

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Pine nuts aren't farmed; they're harvested from forests. The nuts are hidden inside the cones of certain species of pine, such as this pinyon in Utah's Fishlake National Forest. Scott Smith/Corbis hide caption

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Hazelnuts, in all their glory. Ingrid Taylar/Flickr hide caption

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Regular nut consumers had about a 20 percent reduction in all-cause mortality, including lower death rates from heart disease and cancer, a study found. iStockphoto hide caption

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Where In the U.S. do people say pee-kahn over pi-kahn? Joshua Katz answered your burning question by mapping Bert Vaux's dialect survey on regional variations in the continental United States. Courtesy of Joshua Katz hide caption

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