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Excoecaria agallocha L. 1759
pronounced: eks-see-KAIR-ee-uh uh-GAL-oh-kuh
(Euphorbiaceae – the spurge family)
common name: Blind-your-eye Mangrove
Excoecaria comes from the Latin excæco, to make blind. The derivation of agallocha has been more difficult to track down. It would appear to come from the Greek word αγαλοχον (agalochon), first used in a botanical context by the Greek physician and botanist Dioscorides in his book published in about 65 AD, De Materia Medici†. Dioscorides is thought to have borrowed it from a rather inept transliteration of the Hebrew word אהלים (ahalim) made by the translators of the Septuagint when translating Proverbs 7:17. The Hebrew word itself was probably a borrowing from the Sanskrit word aghil, aloes-wood. The translators of the King James Version of the bible merely translated it as ‘aloes’. I would suggest that its meaning in our plant’s specific is ‘sweet-smelling’.
This is a small tree, usually up to about 5 m tall (although it can grow much taller), found in mangrove communities, along tidal streams, or on the margins of tidal salt meadows. It is found from Africa, across the Asian subcontinent to Japan and south-east Asia, to Australia, New Guinea and the Pacific Islands. It has no above-ground roots, but sometimes has spreading surface roots.
The alternate leaves are fleshy, about 6–10 cm long and 2–5 cm wide, shiny bright green; they may have slightly serrate edges, and are pointed at the ends. The leaves, and indeed all parts of the tree, exude a white latex when broken, and this latex can indeed ‘blind-your-eye’, at least temporarily‡, as well as blistering the skin. The young leaves are pinkish; old leaves turn bright red when they are about to drop off.
The tree is dioecious; the flowers are small, occurring in sprays or racemes, the male ‘catkins’ being longer than the female (male 5–10 cm, female 1–4 cm long). When they are in bloom, the trees can look confusingly different. There are a number of male trees on the banks of Butler Creek, Picnic Bay, a few metres back from its mouth. There are some female trees in Nelly Bay, near the school. The flowers are thought to be wind-pollinated, but the sticky pollen may also be transferred by bees, who are common visitors to the trees. The small, round fruit capsules (6–8 mm wide) dehisce when ripe, to disperse the seeds by water. The seeds have an air space under the seed coat to help them float.
Natives in New Guinea use the sap as an ingredient in arrow poison, and also to stun fish. The timber is soft, white, light with a fine grain, and rots quickly. Nevertheless, in Bangladesh the tree is an important source of cheap planks, matches and match boxes, and pulp for paper. The timber is easily transported by water, as it floats. It is also used as firewood, and converted into charcoal.
Medicinally, oil distilled from the wood is used to treat skin infections and stings from marine creatures. Smoke from burning the bark is used to treat leprosy. In the Solomon Islands the latex is taken with coconut milk as a powerful purgative and an emetic. The roots are used to treat toothache and swellings. Modern clinical trials indicate that the plant may have anti-HIV, anti-cancer, anti-bacterial and anti-viral properties.
Caterpillars of the moth Adoxophyes templana, often a pest in citrus orchards, have been found feeding on this plant.
† Concerning Medical Matters
‡ rinse the eye with water for 15 minutes, and seek urgent medical assistance
Information about medicinal qualities of plants, or about their use as medicines, is for interest only, and is not intended to be used as a guide for the treatment of medical conditions.
Photographs taken in Picnic & Nelly Bays 2010, 2015
Page last updated 16th January 2017