The pumpkin tree grows to about 8 m in height. It has pale, corky bark and soft, brittle wood. The ovate to broadly elliptic leaves are 70–200 mm long and 45–100 mm wide; they have glossy uppersurfaces and are pale and sparsely haired beneath. The flowers are large and orange with small red dots, appearing over summer from October to April. The fruit is a black, beaked capsule 15 mm long which holds numerous tiny, wind-dispersed seeds.