Harmsiopanax is a small structurally isolated genus confined to the Malesian Archipelago. The three species here recognized are uniform both in their vegetative and their reproductive features. It has long been recognized that some of the characters of this genus are anomalous within the Araliaceae and a return to its earlier position within the Umbelliferae would have something in its favour. The monocarpic habit is unknown elsewhere in the Araliaceae, but is not uncommon in the Umbelliferae. The character of the fruit, which splits into two dry mericarps, closely approaches the fruit of the Umbelliferae, and the vascularization of the gynoecium (Philipson, 1970) is also characteristic of that family. However, the structure of the leaf-base, the tree stature, and the shape of the petals all incline towards the Araliaceae. This genus and a few other genera from the south-east Pacific region confirm the close relationship between these two families. The earliest known of the three species ranges through Java and the Sunda Islands to Timor and also northwards into Celebes. This species, H. aculeatus, is rather uniform in its characters. Within the Island of New Guinea the forms of the genus are more complex. A species of low to moderate altitudes (sea level to 1800 m) was described early in this century as H. harmsii. This species is confined to the eastern part of the island. It differs from H. aculeatus in several respects, particularly in leaf-shape and in the spherical umbellules borne on a distinct peduncle.