Yucca cernua (Agavaceae: series Rupicolae), a new species from Newton and Jasper counties in eastern Texas

摘要

A new species of Yucca from the series Rupicolae is described from Jasper and Newton counties in eastern Texas. Series Rupicolae is distinguished by its characteristically denticulate leaves and beaked fruits. This new species, Yuccacernua, sp. nov.is described illustrated, and distinguished from other acaulescent species in ser. Rupicolae. The combined characteristics of a tall flowering scape; the tendency of the branches of the in florescence to recurve and droop as they Jengthen; the moderatelyto densely floccose inflorescence; large leaves typically growing erect; relatively short capsules, pistils, and stamens; unique habitat; and disjunct distribution distinguish this species from other acaulescent species in ser. Rupicolae. The rarity ofthis species warrants its consideration as a candidate for state and federal regulatory protection. Also included is a key of the entire or denticulate, non-filiferous leaved North American species of Yucca.