Yucca is confined to the New World and is distributed from Bermuda and the eastern Antilles, through the south Atlantic and Gulf states to Oklahoma and Arkansas, and through New Mexico and northward along the eastern base of the Rocky Mountains to South Dakota, westward to middle California, and southward through Arizona, Mexico, and Lower California to Central America. About thirty species with many varieties and probable hybrids are recognized. Of the species which inhabit the territory of the United States nine assume the habit and attain the size of small trees. The root-stalks of Yucca are used as a substitute for soap, and ropes, baskets, and mats are made from the tough fibres of the leaves. Many of the species are cultivated, especially in countries of scanty rainfall, for their great clusters of beautiful flowers, or in hedges to protect gardens from cattle.
The generic name is from the Carib name of the root of the Cassava.
CONSPECTUS OF THE ARBORESCENT SPECIES OF THE UNITED STATES.
Flower-clusters usually sessile, or short-stalked. Fruit pendulous, with thick succulent flesh; seeds thick; albumen ruminate. Segments of the perianth slightly united at the base. Panicle glabrous or puberulous. Ovary stipitate; leaves sharply toothed on their horny margins, smooth, dark green, slightly concave. 1. Y. aloifolia (C). Ovary sessile. Leaves concave, blue-green, rough on the lower surface. 2. Y. Treculeana (E). Leaves concave above the middle, light yellow-green, smooth. Style elongated. 3. Y. macrocarpa (E, H). Style short. 4. Y. mohavensis (G, H). Panicle coated with hoary tomentum; leaves concave, smooth, light yellow-green. 5. Y. Schottii (H). Segments of the perianth united below into a narrow tube; leaves flat, smooth, dark green. 6. Y. Faxoniana (E). Fruit erect or spreading, the flesh becoming thin and dry at maturity; seeds thin; albumen entire. Leaves rigid, concave above the middle, blue-green, sharply serrate. 7. Y. brevifolia (F, G). Leaves thin, flat or concave toward the apex, nearly entire, rough on the lower surface, dull or glaucous green. 8. Y. gloriosa (C). Flower-clusters long-stalked; fruit capsular, erect, finally splitting between the carpels and through their backs at the apex; seeds thin; albumen entire; leaves thin, flat, filamentose on the margins, smooth, pale yellow-green. 9. Y. elata (E, H).