Description from Flora of China
Shrubs or small trees, deciduous. Branchlets terete or 4-angled; pith solid; winter buds scaly, terminal buds often absent. Leaves opposite, simple or rarely pinnate, petiolate; leaf blade entire, pinnatisect or occasionally lobed. Inflorescences paniculate, terminal or lateral, generally composed of small cymes. Flowers bisexual, sessile or pedicellate. Calyx campanulate, regularly or irregularly 4-toothed or subtruncate, persistent. Corolla funnelform, salverform, or rotate; lobes 4, spreading or upright, valvate, usually cucullate and beaked at apex. Stamens 2, included or exserted. Ovules 2 in each locule, pendulous. Style filiform, shorter than stamens; stigma 2-cleft. Fruit a loculicidal capsule, slightly compressed. Seeds 2 in each locule, flat, narrowly winged; endosperm present; radicle erect.
About 20 species: Afghanistan, India, Japan, Kashmir, Korea, Nepal, Pakistan, Sikkim; SW Asia, SE Europe; 16 species in China.
Most species of Syringa are cultivated as ornamental plants, a few are medicinal.