Zanthoxylum dipetalum is a rare species of tree in the citrus family and in the same genus as Szechuan pepper. It is known by the common name kawa'u and is endemic to the Hawaiian archipelago, where it grows in forests on 3 or 4 of the islands.There are two varieties.Z. d. var. dipetalum is present on Kauai, in the mountains of Oahu, on Hawaii in Hawaii Volcanoes National Park, and possibly on Molokai.Z. d. var. tomentosum is known from fewer than 30 individuals on Hualālai volcano on Hawaii.