It is an upright shrub growing to 1.5 m tall . Its leaves are 15-25 cm long and 1.5-4 cm broad at the base . It is an upright shrub growing to 1.5 metres ( 5 ft ) tall , with leaves 15-25 cm ( 6-10 in ) long and 1.5-4 cm ( 1-2 in ) broad at the base .