Alstonia iwahigensis grows as a medium to large-sized tree up to 45 metres (150 ft) tall, with a trunk diameter of up to 100 centimetres (40 in). The bark is greyish, yellowish or dark brown. Its fragrant flowers feature a yellow or pinkish corolla. The plant is found in forests and on hillsides from sea-level to 500 metres (1,600 ft) altitude. A. iwahigensis is native to Borneo and the Philippines.