Calylophus hartwegii (Benth.) P.H. Raven

Calylophus hartwegii (Benth.) P.H. Raven. Oenothera hartwegii, Hartweg's sundrops, is a species of flowering plant in the evening primrose family Onagraceae. It is native to the desert southwest of the United States, and to northern and western Mexico. A perennial usually 30 to 45 cm tall and 60 cm (24 in) wide, it is used locally as a drought-resistant ground cover.