R. alceifolius is a coarse, vigorous perennial scrambling shrub with a woody rootstock, which reproduces by seed and layering. Stems robust, thick primary canes to 5 m long, covered with a felt of dense brown hairs and scattered recurved prickles up to 5 mm long, erect at first then arching and scrambling over other plants; short secondary canes producing flowers develop in the leaf axils of primary canes in the second growth season. Leaves green, alternate, simple, to 12.5 cm across and 20 cm long, bullate above, velvety brown below due to a dense covering of reddish hairs; deeply notched at the base, with 5 to 7 shallow but finely serrated lobes. Petioles 3-4.5 cm long. There are leafy stipules up to 15 mm long at the base of the petioles. Flowers white, 1.5 to 2 cm in diameter, in clusters at ends of short secondary canes, subtended by brown finely divided bracts; calyx covered at the base with brown velvety hairs. Fruit a succulent aggregate ‘berry’ of about 150 1-seeded segments or drupelets, red when ripe. Seed black, small, subglobular. Root a short woody rootstock giving rise to a sparsely branched main root with a number of fibrous laterals in the upper soil layers.
Several distinct ecotypes are recognized in SE Asia: a form with large leaves in Java, a form with small leaves in northern Vietnam, and a form with hairy leaves in Thailand and Laos.