The vast southwest desert region of North America contains many fascinating wild plants, but none are more intriguing than the Mexican jumping bean. Jumping beans are commonly sold in novelty shops and by street vendors on both sides of the border, and probably everyone has marveled at their erratic movements, or heard a fabulous tale about them. In the regions where they grow wild, they are collected and sold to local dealers who export them to the United States. The actual jumping "bean" is not a bean at all. It is produced by a native shrub or small tree that grows wild in the deserts of mainland Mexico and in the rugged Cape region of Baja California. Probably the most interesting thing about Mexican jumping bean shrubs are the remarkable "beans" that jerk and roll about with seemingly perpetual motion. It is doubtful (or very rare) that they actually "jump" above the surface of the ground, but they can certainly roll and tumble along in different directions. Just as pineapples are not apples and peanuts are not nuts, the jumping bean is not a bean, nor is it a seed. It is actually a small, thin-shelled section of a seed capsule containing the larva of a small gray moth called the jumping bean moth (Laspeyresia saltitans). After consuming the seed within the capsule section, the robust, yellowish-white larva has the peculiar habit of throwing itself forcibly from one wall to the other, thereby causing the jumping movements of the capsule. Mexican jumping bean capsules typically separate into three parts or sections, some of which contain a moth larva. It is these separate sections (technically called carpels) that are sold as "jumping beans."
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