Liana. Leaves with petioles swollen at the base and apex, lamina not or only slightly peltate, ± ovate, penninerved. Inflorescences cauliflorous, fasciculate. Seed broadly ellipsoidal, covered with a reticulate membrane;
Asia-Tropical: New Guinea present, New Britain present, New Ireland present
Malesia: New Guinea (incl. New Britain, New Ireland). Monotypic.
BECCARI stated that the cotyledons are fused together into a solid mass from which the radicle is not differentiated, and that in these respects Macrococculus differs from Pycnarrhena. In the fruit of CLEMENS 631, however, the cotyledons are free, and when split apart the small radicle is discernible lying between the cotyledons at one end. Although Macrococculus appears to be very closely allied to Pycnarrhena, it is desirable, I feel, to maintain it as a distinct genus which can be distinguished especially by the stamens with their distinctive tongue-like prolongations and well developed, flattened filaments. The large fruits with a thick and bony endocarp, the more or less ovate, penninerved leaves and numerous sepals are further diagnostic features of Macrococculus.