Sparingly branched or single-trunked often monocarpic trees, up to 18 m. Flowers in very large, repeatedly branched, terminal panicles which develop after the leaves have fallen. Flowers hermaphrodite or with hermaphrodite flowers on terminal and male flowers on basal branches. Petals 5, free, valvate with a broad base. Stamens 5, dorsifixed, versatile, introrse. Ovary inferior, narrowly obconic, densely bristly; Fruit consisting of 2 dry mericarps, each 3-ribbed and bearing a persistent slightly hooked style.
Asia-Tropical:, Jawa (Jawa present); New Guinea present; Sulawesi (Sulawesi present) Lesser Sunda Is: present
Malesia: 3 spp. from Java, the Lesser Sunda Is., Celebes, and New Guinea.
Harmsiopanax is a small structurally isolated genus confined to Malesia. The three species 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 Araliaceae and a return to its earlier position within Umbelliferae would have something in its favour. The monocarpic habit is unknown elsewhere in Araliaceae, but is not uncommon in Umbelliferae. The character of the fruit, which splits into two dry mericarps, closely approaches the fruit structure of Umbelliferae, and the vascularization of the gynoecium is also characteristic of that family. However, the structure of the leaf-base, the woody habit, and the shape of the petals all incline towards Araliaceae.