''Excoecaria agallocha'', a

mangrove A mangrove is a shrub or tree that grows mainly in coastal saline water, saline or brackish water. Mangroves grow in an equatorial climate, typically along coastlines and tidal rivers. They have particular adaptations to take in extra oxygen a ...

species A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...

, belongs to the

genus Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...

Excoecaria ''Excoecaria'' is a plant genus of the family (biology), family Euphorbiaceae, formally described by Linnaeus in 1759. The genus is native to the Old World Tropics (Africa, southern Asia, northern Australia, and assorted oceanic islands). Etymol ...

'' of the

family Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...

Euphorbiaceae Euphorbiaceae (), the spurge family, is a large family of flowering plants. In English, they are also commonly called euphorbias, which is also the name of Euphorbia, the type genus of the family. Most spurges, such as ''Euphorbia paralias'', ar ...

. The species has many common names, including blind-your-eye mangrove, blinding tree, buta buta tree, milky mangrove, poisonfish tree, and river poison tree. Most of the names refer to its toxic properties or its propensity to cause blindness when its

latex Latex is an emulsion (stable dispersion) of polymer microparticles in water. Latices are found in nature, but synthetic latices are common as well. In nature, latex is found as a wikt:milky, milky fluid, which is present in 10% of all floweri ...

comes into contact with the eyes. This plant grows in saline or brackish water in

tropical The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

mangrove forests, in a distribution bounded to the west by

India India, officially the Republic of India, is a country in South Asia. It is the List of countries and dependencies by area, seventh-largest country by area; the List of countries by population (United Nations), most populous country since ...

, to the north by

Bangladesh Bangladesh, officially the People's Republic of Bangladesh, is a country in South Asia. It is the List of countries and dependencies by population, eighth-most populous country in the world and among the List of countries and dependencies by ...

, to the south by

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

. Within Australia, it thrives from northern

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

along the northern coastline around to

Western Australia Western Australia (WA) is the westernmost state of Australia. It is bounded by the Indian Ocean to the north and west, the Southern Ocean to the south, the Northern Territory to the north-east, and South Australia to the south-east. Western Aust ...

Description

Mangrove swamps form a type of coastal

wetland A wetland is a distinct semi-aquatic ecosystem whose groundcovers are flooded or saturated in water, either permanently, for years or decades, or only seasonally. Flooding results in oxygen-poor ( anoxic) processes taking place, especially ...

found in the tropics and subtropics. Within a mangrove forest, the most salt-tolerant species occur near the ocean. ''Excoecaria agallocha'', known as a back mangrove, is found at higher elevations back away from the ocean where salinity is lower. Mangroves of this plant surround the ancient

Thillai Chidambaram Temple Thillai Nataraja Temple, also referred as the Chidambaram Nataraja Temple, is a Hindu temple dedicated to Nataraja, the form of Shiva as the lord of dance (cosmic dancer). This temple is located in Chidambaram, Tamil Nadu, India. This temple ...

Tamil Nadu Tamil Nadu (; , TN) is the southernmost States and union territories of India, state of India. The List of states and union territories of India by area, tenth largest Indian state by area and the List of states and union territories of Indi ...

. This small tree species may grow up to 15 m high. Trees are either male or female (dioecious). Male flowers form drooping tassels, while female flowers appear as shorter spikes. Pollinators such as bees commonly visit the flowers. The fruit is a small dark capsule. The milky

of ''Excoecaria agallocha'' is very poisonous and powerfully irritant, which is not unusual in milky species of plant in the family Euphorbiaceae. Contact with skin causes irritation and rapid blistering; slight contact with eyes can cause temporary blindness, hence the common names that refer to blindness. Even the generic name is from the Latin for "blinder".

William Bligh William Bligh (9 September 1754 – 7 December 1817) was a Vice-admiral (Royal Navy), Royal Navy vice-admiral and colonial administrator who served as the governor of New South Wales from 1806 to 1808. He is best known for his role in the Muti ...

in his book ''Voyage to the South Sea'' mentioned that he was already aware of this hazard when he embarked on the voyage that ended in the notorious

mutiny on the Bounty The mutiny on the ''Bounty'' occurred in the South Pacific Ocean on 28 April 1789. Disaffected crewmen, led by acting-Lieutenant Fletcher Christian, seized control of the ship, , from their captain, Lieutenant (navy), Lieutenant William Bli ...

, having learned of it in 1777 from Captain

James Cook Captain (Royal Navy), Captain James Cook (7 November 1728 – 14 February 1779) was a British Royal Navy officer, explorer, and cartographer famous for his three voyages of exploration to the Pacific and Southern Oceans, conducted between 176 ...

during the time that he served as Cook's

sailing master The master, or sailing master, is a historical rank for a naval Officer (armed forces), officer trained in and responsible for the navigation of a sailing ship, sailing vessel. In the Royal Navy, the master was originally a warrant officer who ...

. Several of the men that Cook had sent ashore to cut wood had been blinded for a time. He accordingly instructed his men not to cut that type of tree when he sent them ashore in Tahiti to gather wood and water in 1789. It was just as well that he did so, because even the smoke from the burning wood is poisonous and can harm the eyes, so it would not have been useful as fuel.

Taxonomy

''Excoecaria agallocha'', a

, belongs to the

'' of the

Ecology

The latex produced by ''E. agallocha'' contains a variety of

phorbol Phorbol is a natural, plant-derived organic compound. It is a member of the tigliane family of terpene, diterpenes. Phorbol was first isolated in 1934 via the hydrolysis of croton oil, which is derived from the seeds of the purging croton, ''Crot ...

-like toxins such as excoecariatoxin which are powerful irritants to the skin, eyes and mucous membranes. Despite the powerful chemical defense mechanisms of this plant, ''E. agallocha'' is the sole food source for the

larva A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...

e of the mangrove jewel bug ('' Calliphara nobilis''), a

phytophagous A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet (nutrition), diet. These more broadly also encompass an ...

species of jewel bug found in

mangrove forests in some parts of Asia. Like many other species of

aposematic Aposematism is the Advertising in biology, advertising by an animal, whether terrestrial or marine, to potential predation, predators that it is not worth attacking or eating. This unprofitability may consist of any defenses which make the pr ...

scutellerids, ''C. nobilis'' is able to sequester chemical compounds from its host plants that are toxic to their predators, and use them towards its own defenses. These chemical compounds are concentrated and stored in a pair of scent glands located on the

metathorax The metathorax is the posterior of the three segments in the thorax of an insect, and bears the third pair of legs. Its principal sclerites ( exoskeletal plates) are the metanotum (dorsal), the metasternum (ventral), and the metapleuron (lateral ...

of the adults and

nymphs A nymph (; ; sometimes spelled nymphe) is a minor female nature deity in ancient Greek folklore. Distinct from other Greek goddesses, nymphs are generally regarded as personifications of nature; they are typically tied to a specific place, land ...

. When these insects are threatened or handled, they can secrete an irritating and toxic fluid from these glands as a deterrent to potential predators.

Uses

Even dried and powdered leaves retain the poison and can kill fish very quickly or be used on a poison dart. ''Excoecaria agallocha'' has been found to have various medicinal and pharmacological benefits, including the treatment for epilepsy, ulcers, leprosy, rheumatism, and paralysis. This plant species appears to be quite chemically complex.Konoshima,T, T. Konishi, M. Takasaki, K. Yamazoe, and H. Tokuda. 2001. Anti-tumor-promoting activity of the diterpene from Excoecaria agallocha. II Biological and Pharmaceutical Bulletin 24:1440-1442.

References

External links

Milky mangrove in Australia

Biology of mangroves
{{Taxonbar, from=Q5419710 agallocha Plants described in 1759 Flora of Asia Flora of Australia Taxa named by Carl Linnaeus Dioecious plants Flora of the Central Indo-Pacific