Metastelma arizonicum A. Gray Metastelma arizonicum A. Gray in Proc. Amer. Acad. Arts 19(1): 85. 1883 ["1884"] sec. Sánchez-Escalante & Gilbert 2021=Metastelma watsonianum Standl. in Contr. U.S. Natl. Herb. 23: 1175. 1924 syn. sec. POWO 2019