Sea Poison Tree (Barringtonia asiatica) is a salt-tolerant landscape tree, commonly associated with coastal areas, with a natural range extending from tropical Africa, through India to Southeast Asia, Australia and the Pacific.
It is typically 30 to 50 feet (10 to 15 m) tall and develops a short trunk with a low-branching structure and a densely branched, wide-spreading rounded crown. The leaves are large, oval, or nearly so, glossy green, leathery and showy in whorled clusters at the tips of the branches.
It blooms on and off throughout the year, with large, showy, white, tulip-like flower buds that open at night to reveal their long, hair-like filaments, which are white with pink tips and collectively resemble a powder-puff when extended.
The flowers are followed by four-sided, woody fruit about the size of a juvenile coconut. Green, when young they mature to a dull grey-brown and like a coconut, will float and drift on the ocean until they land on new shores.
Growing Conditions and General Care
Grows naturally in moderately humid to humid tropical coastal climates, generally in areas with annual lows of 68 to 77 °F (20 to 25 °C), annual highs of 81 to 93 °F (27 to 34 °C), annual rainfall of 1000 to 4000 mm and a dry season of 6 months or less.
Sea Poison Tree grows best in a fertile, humid, well-drained soil. It prefers a position in full sun or light shade. Established plants are fairly drought tolerant and very tolerant of saline conditions and salt-laden winds. They thrive in the wild, where their roots dabbling in the brackish waters of lagoons, inlets, estuaries, and seasonally flooded coastal regions.
New plants are usually grown from seed. It performs best on free-draining sand and loam soils of a slightly acid to alkaline nature, generally with a pH of 6.0 to 8.5 and on sites with full sun exposure. It has good tolerance to salt, wind, tidal flooding, and coral derived limestone soils.
The flowers are short-lived, opening for one night only then lose their petals, which fall to the ground creating litter along with the fallen leaves. The fruits are highly poisonous.
It is commonly cultivated in seaside gardens and landscapes for its showy foliage, flowers, and the welcome shade that it offers against the hot midday sun. Its high tolerance to salt, tidal flooding, and strong winds make it especially suited to sites on or near the shoreline, where it also serves as a natural windbreak against strong sea breezes.
Because all parts of the tree contain saponin, which is a poison, the seeds and other parts of the plant are pounded and used to stun fish in freshwater streams.
Seeds are used to get rid of intestinal worms, and the heated leaves are used to treat stomachache and rheumatism. Juice from the seeds is used to seal paper umbrellas and to kill lice and other external parasites.