Angiopteris evecta

Angiopteris evecta is a very large fern found in parts of Southeast Asia and the western Pacific. It is naturalised in Hawaii, Jamaica, Costa Rica and Cuba. Common names in English include King fern, Giant fern, Elephant fern, Oriental Vessel fern, Madagascar tree fern, and Mule's Foot fern. In other languages it is known as 莲座蕨 (lian zuo jue) in Chinese and fougère royale in French. Localised common names include e'e (Cook Islands); helecho elefante (Cuba); nahe (French Polynesia); polato (Niue); bersarm, demarm, and dermarm (Palau); nase and oli oli (Samoa); and hulufe tano, hulufe vai, and ponga (Tonga).
Description.
"Angiopteris evecta" is a self-supporting evergreen perennial fern with very large bipinnate fronds. The trunk-like rhizome is massive, measuring up to in diameter. The older portions of the rhizome lie on the ground while the newer growth may rise vertically up to high. The arching, glossy green fronds, which emerge from the top of the trunk, may reach up to wide and long, with the fleshy green petiole (leaf stem) making up of that length. They are said to be the longest fern fronds in the world. Despite their size they have no strengthening tissues, instead they are supported entirely by the turgor pressure of the sap. The rachises, pinnae and pinnules are all pulvinate (swollen at the base). Sporangia are borne on the underside of the pinnules, very close to the margin, in clusters of 5 to 8 opposite pairs. On either side of the petiole where it arises from the trunk there are flat, rounded, leathery, ear-shaped stipules, known as "auricles", which can measure up to . Overall dimensions of this fern can be up to high by wide.
Taxonomy.
"Angiopteris evecta" is the type species of the genus Angiopteris. It was originally named "Polypodium evectum" and described by Georg Forster in 1786, but was reclassified in 1796 by Georg Franz Hoffmann. There are many synonyms (see Synonyms section below) which are considered by some authorities to potentially be distinct species, calling for a more thorough taxonomic investigation.
Etymology.
The genus name comes from the Ancient Greek "aggeion", a vessel, and "pteris", a fern. The species epithet derives from the Latin adjective "evectus" meaning swollen or inflated.
Evolution.
Fossil records in Paleozoic rocks have been found which are very similar to "Angiopteris evecta", indicating that the species has been in existence for around 300 million years. The geographically isolated communities seen today point to favourable climatic conditions being more widespread in the past.
Distribution and habitat.
"Angiopteris evecta" is native to southeast Asia, from Singapore through Indonesia, Papua New Guinea and Australia to Melanesia, Micronesia and Polynesia. It has been introduced to most of the rest of tropical Asia, as well as Madagascar and parts of the tropical Americas.
The species grows in very rich soils, often of volcanic origin and prefers a very warm wet climate. It is most commonly found as an understorey plant in well developed rainforest, especially along creek banks in deep sheltered gullies where there is good drainage but also a plentiful supply of fresh water. The preferred annual mean temperature range is and annual precipitation between . It may grow at altitudes from sea level to 
Cultural uses.
The starchy rhizomes are eaten after long processing to remove toxins, used to perfume coconut oil, to flavour rice and to produce an intoxicating drink. The 1889 book "The Useful Native Plants of Australia" records Indigenous Australians ate the pith of this fern.
Conservation status.
The conservation status of "Angiopteris evecta" varies from place to place. For example in Australia's Northern Territory it is listed as vulnerable, with only one small population in north eastern Arnhem Land; in New South Wales, where suitable habitat is restricted to a small area in the north east corner of the state and only a single, non-reproductive specimen is known, it is listed as endangered. However in Queensland, which sits in between the previous two and where there is an abundance of suitable habitat, it is listed as least concern.
Invasive potential.
When introduced to an area with a suitable climate, "Angiopteris evecta" can establish dense stands that inhibit local species. It is listed as invasive in Costa Rica, Cuba, Jamaica and Hawaii, where in each case it has escaped from plantings in botanic gardens. It has also been introduced to many tropical countries and has repeatedly escaped from cultivation.
Synonyms.
Plants of the World Online lists 74 synonyms for "Angiopteris evecta":
External links.
Map of observations of "Angiopteris evecta" at the Australasian Virtual Herbarium