Trees, trunk and branches armed with simple or branched spines. Leaves uni and bipinnate in the same specimen, stipules small. Inflorescence racemose, fasciculate or cymose Flowers bracteate, bisexual and unisexual, small, greenish or whitish. Calyx-tube turbinate-campanulate, with 5-3 subequal lobes. Petals 5-3, sessile, slightly unequal, imbricate. Stamens 10-6, free. Ovary in male flowers rudimentary, minute or absent; in bisexual flowers subsessile; ovules numerous to 2, style short, stigma terminal. Fruit ovate or elongated, compressed, 2-valved or indehiscent.