Tree 10-15 m. Leaves membranous, elliptic-oblong to oblong-lanceolate, 11-25 by 3.5-7 cm, base (long-)attenuate, apex acute-acuminate; Inflorescences ± behind the leaves, 2 (or 3) times branched; Fruits 2-5 per infructescence, short-ellipsoid to subglobose, 1.1-1.2 by 1-1.1 cm, with hairs 0.1 mm or less, drying brown, with scattered small tubercles;
Horsfieldia decalvata superficially resembles several other species, including the widespread H. laevigata, H. moluccana, and H. tuberculata, but is distinguishable by its finely pubescent, pear-shaped male flowers, erect anthers, pubescent ovaries, and small, subglobose, finely pubescent fruits. In Horsfieldia laevigata the male bud is more spherical in outline, and the fruit is much larger and pubescent. Horsfieldia moluccana has incurved anthers and glabrous fruits. Horsfieldia tuberculata also has pear-shaped flowers which are generally glabrous, and it has larger, glabrous fruits.