Description from Flora of China
Trees, unarmed. Leaves bipinnate, with numerous pinnae and leaflets. Inflorescences solitary and axillary, or several at apices of branches, large and clavate or depressed globose, pedunculate. Flowers very numerous. Fertile flowers (bisexual) at upper part of heads, yellow to red, lower sterile ones (male or neuter) white or red. Calyx cylindric; teeth 5, very short and imbricate. Petals 5, linear-spatulate, free or connate to middle. Stamens 10, free or connate at base and adnate to corolla; anthers oblong, usually tipped by a gland. Ovary sessile or stipitate; ovules numerous; style filiform; stigma terminal. Petals of lower sterile flowers often free. Staminodes 10, in a long bundle, free distally, filiform. Legume straight or curved, oblong or elongate, compressed, rather woody or fleshy, 2-valved. Seeds transverse, ovoid, thick or compressed; pleurogram if present ± elliptic.
About 35 species: tropical regions of Africa, the Americas, and Asia; two species (both introduced) in China.