The soap tree yucca takes its name from the fact that the original inhabitants of the USA and Mexicans used the sap from the trunk and the roots as soap to wash themselfes and their clothes. This yucca's leaves are pointed, narrow and covered in small white hairs or strings.
Yucca elata is slightly less hardy than Yucca faxoniana but can certainly tolerate frost in winter if not too wet in a well drained soil. Like all Yuccas keeps elata also enjoys full sun. Rather rare on the market but available now.