Yucca, a group of about 30 species of plants native chiefly to the deserts of the southwestern United States, Mexico, and Central America. Many yuccas bear large, showy clusters of cup-shaped flowers, and a number are cultivated throughout the world.
The flowers are usually waxy-white or greenish-white. Yuccas have stiff, swordlike leaves. Their fruits are dry capsules or fleshy berries. The fruits provided food for the Indians, and the leaves furnished fiber for rope, matting, and baskets. The roots of some kinds were used as soap.
The Joshua tree grows to more than 30 feet (9 m) tall. Its trunk is irregularly branched, and daggerlike leaves grow at the ends of the branches. The Spanish bayonet, which grows to 25 feet (8 m), bears clusters of swordlike leaves atop the trunk. Its blossom is the state flower of New Mexico. The Adam's needle is a nearly stemless yucca whose leaves, which are up to 2 feet (75 cm) long, appear to grow from the ground.
The yucca plant and the yucca moth depend on each other for survival. The plant can be pollinated only by the moth; and the moth's caterpillars can get food only from the yucca plant. After gathering a ball of pollen, the yucca moth deposits its eggs in the ovary of a flower and then pollinates the flower by stuffing the pollen down its funnel-shaped pistil. The caterpillars feed on the seeds, but they mature and pupate before they eat all of them.
The Joshua tree is Yucca brevifolia; the Spanish bayonet, Y. aloifolia; the Adam's needle, Y. filamentosa. The genus Yucca belongs to the agave family, Agavaceae. The yucca moth is Pronuba yuccasella.