Pipturus albidus, known as mamaki (sometimes waimea, for its resemblance to olomea) in Hawaiian and known as Waimea pipturus in English, is a species of flowering plant in the nettle family, Urticaceae, that is endemic to Hawaii. It inhabits coastal mesic, mixed mesic, and wet forests at elevations of . Mamaki is a small tree that reaches a height of and a trunk diameter of .