Barringtonia racemosa can tolerate salt water and therefore thrives under coastal and estaurine conditions. It also grows well under dry conditions where frost does not occur. The chief dispersal agent for the buoyant seeds is the tide. Although there are no records of animals eating the fruit, the presence of the trees up to 1 000 m above sea level points to an as yet unknown animal as a dispersal agent. It flowers twice a year: in spring and again from January to April. The strong scent produced by the flowers at night attract moths and nectar-feeding bats. After the flowers (petals and stamens) are shed, the inflorescences are often crowded with ants that are attracted to the nectar. It is the larval food plant for the butterfly Coeliades keithloa.
Barringtonia racemosa has a straight, unbranched stem that leads to a rounded crown and is usually 4-8 m tall, but occasionally reaches 15 m. The bark is greyish brown to pink with white blotches and raised dots and lines. The branches are marked with leaf scars.
The flowers are produced on hanging racemes up to 1 m long. The buds are pinkish red and split open to bring forth masses of delicate stamens in white sprays up to 35 mm wide, which are often tinged with pink. The flowers give off a pungent, putrid yet faintly sweet odour in the morning. The fruit are quadrangular, 65 x 40 mm. Each fruit contains a single seed surrounded by spongy, fibrous flesh that provides the buoyancy that allows the fruit to be carried off with the tide.
Distribution and habitat
Barringtonia racemosa is mainly a coastal species that thrives under very humid, moist conditions. It is common along tropical and subtropical coasts in the Indian Ocean, starting at the east coast of South Africa. It is also common in Mozambique, Madagascar, India, Sri Lanka, Malaysia, Thailand, Laos, southern China, northern Australia, the Ryukyu Islands of Japan and a number of Polynesian islands. It does grow well under dry conditions but it cannot tolerate even mild frost.
Uses and cultural aspects
The seeds, bark, wood and roots contain the poison saponin and is used to stun fish. The bark, which also has a high tannin content, is frequently used in powdered form for this purpose. Extracts from the plant are effective insectides and are also used medicinally in the East; in South Africa the Zulus use the fruit to treat malaria. In Bengal the seeds are used to poison people and coconut is said to be the antidote. The young leaves are edible and the bark is often used for cordage.