C. siliqua attains a height of 15-17 m and can have a trunk 85 cm in diameter by the time it is 18 years old. The leaves are pinnate with 6-10 opposite leaflets. The leaflets are oval and rounded at the apex, 2.5-6.25 cm long, dark green and leathery. The red flowers are small and borne in clusters. Flowers bloom from September to November on older wood in the Mediterranean.
Separate trees are male, female or hermaphroditic.
Fruit shape is oblong, flattened, straight or slightly curved and with a thickened margin. Ripening late in the summer, during bloom, the fruit is shiny, tough and fibrous. The fruit contains a soft, pale brown pulp and 5-15 flattened, hard seeds. When the pod is fully ripe and dry, the loose seeds rattle. The impacts of this new invader are unknown.