A number of species of Yucca L. (Agavaceae) have gained considerable popularity in mild-climate horticulture the world over. Two such large-growing, arborescent species are especially popular in regions where they can be planted outdoors, for example in regions experiencing tropical, subtropical, Mediterranean, and even some temperate, climates, while one of them is also popular as an indoor plant in regions with a similar, or more severe, continental-type, climate. Three names, Yucca gigantea Lem. (1859), Yucca guatemalensis Baker (1872), and Yucca elephantipes Regel ex Trel. (1902) are applied to these two species. However, it has also been suggested that these three names all refer to a single entity. If so interpreted, the name that has priority, and must therefore be adopted, is Yucca gigantea, with Yucca elephantipes and Yucca guatemalensis being synonyms. We propose that the differences between Yucca guatemalensis, the publication date of which precedes that of Yucca elephantipes, and Yucca gigantea warrant their separate recognition, with Yucca elephantipes being synonymous with Y. guatemalensis.