Seeds from Yucca smalliana Bear Grass. This perennial plant has a large rosette of evergreen basal leaves that spread outward in all directions. Individual basal leaves are up to 30 inches long and 2 inches across. They are blue gray or green gray and linear in shape with sharp tips. It is very showy when in bloom in May to June. Full sun, mesic to dry conditions, and sandy soil. The tall spikes of bell shaped, creamy white flowers last for two or three weeks and perfume gardens with evening fragrance. However, other kinds of soil are tolerated as well, including those that contain loam, clay, or rocky material. Individual plants are long lived and require little care to maintain. The leaf fibers of various Yuccas and Agaves can be mechanically extracted and used to make rope with very high tensile strength. Hardy in zones 5 to 10.