﻿AbstractEpimediumlongnanense, a new species ofEpimedium(Berberidaceae) from Longnan Prefecture, Gansu Province, China, is here proposed and illustrated.E.longnanensehas large flowers with petals possessing long spur and obvious basal lamina, and thus should be grouped into seriesDavidianae. The species closely resemblesE.flavumof ser.Davidianaein morphology. However, it can be easily distinguished by its elongated rhizome (vs. compact), trifoliolate leaves (vs. five leaflets, sometimes trifoliolate), pale pink or purplish-red inner sepals with 6–8 × 2–3 mm (vs. pale sulphur-yellow, ca. 11 × 4 mm).