Yucca arkansana shows considerable variation, particularly in the eastern part of its range. S. D. McKelvey (1938-1947) described var. paniculata and suggested that it is an eastern extension of the species with a taller, paniculate, and pubescent inflorescence. Yucca arkansana approaches Y. louisianensis, which we have reduced to synonymy under Y. flaccida. K. H. Clary´s (1997) DNA consensus tree places Y. arkansana and Y. louisianensis adjacent to one another.