Zanthoxylum dipetalum var. tomentosum is a long-lived perennial and a tree in the citrus family (Rutaceae). It has alternate leaves comprised of three to seven leathery, elliptical, gland-dotted, smooth-edged leaflets. The undersurface of the leaflets is densely covered with fine, short hairs, and the lowest pair of leaflets is often strongly reduced. This variety is distinguished from Zanthoxylum dipetalum var. dipetalum by the hairs on the undersurface of the leaflets. It is distinguished from other Hawaiian species of the genus by its reduced lower leaflets, the presence of only one joint on some of the leaflet stalks, and the large seeds.