Asclepias nyctaginifolia A. Gray Asclepias nyctaginifolia A. Gray in Proc. Amer. Acad. Arts 12: 69-70. 1876 sec. Ulloa Ulloa & al. 2018=Asclepias wrightii Greene ex A. Gray in Proc. Amer. Acad. Arts 16: 102. 1881 syn. sec. The Plant List 2013