You can find three species of yucca growing wild in Missouri. Spanish bayonet was introduced from the Southwest and has escaped from cultivation, but our two yuccas, both called soapweeds, are native.
Spanish bayonet, or Adam’s needle (Yucca smalliana; formerly Y. filamentosa or Y. flaccida), has stout, scaly flower stalks topped by a panicle of many flowers, arising above a large basal cluster of stout, sharp-pointed, leathery leaves. The flowers are cuplike, with 3 sepals and 3 petals, 2 inches across, and creamy white. Blooms May–July. Leaves are basal, stiff, narrow, sharply pointed, to 2½ feet long, often with fibrous edges. Fruit is a large, papery capsule with hundreds of flat, black seeds.
Soapweed (Yucca glauca) is a native that, in Missouri, is found only in the northwestern corner of the state (Holt and Atchison counties). The base of the flowering portion of the flower clusters is not raised above the leaves, and the leaves are spine-tipped.
Another soapweed, Y. arkansana, is a native that in our state is found only in the southern portion of Missouri’s Ozarks, along the Arkansas border. It is similar to Y. glauca, but it has softer leaves that are not spine-tipped.