Excoecaria agallocha aka River Poisontree

Excoecaria agallocha has the common name milky mangrove. It belongs to the spurge family, Euphorbiaceae. Its native range spans tropical and subtropical parts of Asia. It reaches as far as the western Pacific. Records list southern China, India, Southeast Asia, Australia and Pacific islands. It grows in mangrove woods and forests reached by tides. It also grows on brackish ground and in coastal rice fields. Most of these sites lie on low ground near sea level.

The plant forms a shrub or tree with low branches. It may stay green year-round or lose its leaves for a short time. One source gives a height of about 49 feet [15 metres]. The wider reported range reaches 33–98 feet [10–30 metres]. The trunk branches near its base and has stilt roots. Its white wood feels soft and spongy. Each plant bears either male or female flowers. Both sexes must grow there to form fruit and seeds.

This species suits the warmth of the tropics and subtropics. It grows best with daytime temperatures of 20 to 30°C. The source gives a wider range it can bear: 15–37°C. It needs full sun and grows in many fertile soils. It can also cope with salt in the soil. Its preferred soil pH falls between 6.5 and 7. It can bear a wider pH range of 6–8. Sources give a broad range for its rainfall needs. It grows best with annual rainfall of 1,000–2,000 millimetres.

People grow the tree for its looks. They also collect wild plants for local remedies. Some wood serves as incense, while the roots can serve as floats. Folk medicine uses its latex, resin, bark and distilled oil. These records show uses, not proof that treatment is safe. The species still grows across a wide area. Yet coastal development has cut its numbers. Useful Tropical Plants cites a 2011 IUCN review. That review rates the species as Least Concern. This broad rating does not mean local threats have gone.

Every part of this tree is poisonous. The draft records no edible uses. Cuts release harsh latex that can blister skin and harm eyes. This risk explains names such as blinding tree. Thus, cutting or handling damaged branches poses a clear risk. People have used the latex to poison fish. Crushed leaves placed in water can also stun fish. Its toxic sap matters when choosing where to plant it for its looks.