The leaves are evergreen in the south of the range , but deciduous farther north where winters are colder . They are oval-elliptic with an acute apex , 3-7 cm long and 2-4 cm broad , with a smooth or very finely toothed margin . The leaves are evergreen in the south of the range , but deciduous further north where winters are colder ; they are oval-elliptic with an acute apex , 3-7 cm long and 2-4 cm broad , with a smooth or very finely toothed margin .