THE GENUS HESPEROYUCCA (AGAVACEAE) IN THE WESTERN UNITED STATES AND MEXICO: NEW NOMENCLATURAL COMBINATIONS

Within Yucca L., as traditionally circumscribed, is a group of species, herein recognized as Hesperoyucca (Engelm.) Baker, that has morphological, phenological, and pollinator characteristics markedly different from all others. These characteristics include a loculicidal capsule, a capitate stigma, and glabrous, swollenfilamentstli.il u uu< lu*d loth lm\< r p ut ol ih< t pals and that draw away from the ovary when the tepals open. These filaments bear bulbous anthers with tufted pubescence that bend toward the stigma and dehisce laterally (Fig. 1). Their pollen is produced in a glutinous mass. The sole pollinator of Hesperoyucca is Tegeticula maculata Riley, a species of yucca moth (Riley 1892; Trelease 1893, 1902; Powell &Mackey 1966; Davis 1967; Segraves &Pellmyr 2001). The other approximately 47 species of Yucca are visited by the remaining spe-