Trees, shrubs or climbing vines. Stipules often fall early; Leaves simple, entire, apex concave or divided into 2 lobes, sometimes deeply divided into 2 free leaflets at the base; There are three or more basal veins, and the midvein often protrudes between the two lobes to form a small awn tip. Flowers bisexual, rarely unisexual, forming racemes, corymbs or panicles; Bracts and bracteoles usually caducous; Receptacle is short gyro-shaped or elongated into a cylinder; Calyx cup-shaped, Buddha-shaped or divided into 5 sepals at anthesis; 5 petals, slightly unequal, usually pedicellate; Fertile stamens 10, 5 or 3, sometimes 2 or 1 piece, anthers dorsifixed, longitudinally dehiscent and rarely perforated; Several staminodes (or sterile stamens) with smaller anthers and no pollen; Pseudostamens acuminate at the top, without anthers, sometimes palmately connate at the base; Disk flat or fleshy and swollen, sometimes lacking; Ovary usually stipitate, with 2 or more ovules. The style is slender, filiform or stubby, and the column is head-shaped or shield-shaped. Pods are oblong, banded or linear, usually flat, dehiscent and indehiscent; Seeds round or oval, flat, with or without endosperm, radicle straight or nearly straight.
About 600 species, distributed in tropical regions of the world. There are 40 species of 4 subspecies 1 1 varieties in China, which are mainly produced in the south and southwest.