Erythrina Caffra Tree

''Erythrina'' is a genus of plants in the pea family, Fabaceae. It contains about 130 species, which are distributed in tropical and subtropical regions worldwide. They are trees, with the larger species growing up to in height. The generic name is derived from the Greek word , meaning "red", referring to the flower color of certain species.

Names

Particularly in horticulture, the name coral tree is used as a collective term for these plants. Flame tree is another vernacular name, but may refer to a number of unrelated plants as well. Many species of ''Erythrina'' have bright red flowers, and this may be the origin of the common name. However, the growth of the branches can resemble the shape of sea coral rather than the color of '' Corallium rubrum'' specifically, and this is an alternative source for the name. Other popular names, usually local and particular to distinct species, liken the flowers' red hues to those of a male chicken's wattles, and/or the flower shape to its leg spurs. Commonly seen Spanish names for any local species are ''bucaré'', ''frejolillo'' or ''porotillo'', and in Afrikaans some are called ''kafferboom'' (from the species name ''Erythrina caffra''). ''Mullumurikku'' is a widespread name in Kerala.

Description and ecology

Not all species of ''Erythrina'' have bright red flowers; the Wiliwili (''E. sandwicensis'') has extraordinary variation in its flower colour, with orange, yellow, salmon, green and white all being found within natural populations. This striking color polymorphism is also found in ''Erythrina lysistemon'' and ''Erythrina caffra''.

All species except the sterile hybrids ''E.'' × ''sykesii'' and ''E.'' × ''bidwillii'' have legume-type fruit, sometimes called pods, containing one or more seeds. The resilient buoyant seeds are often carried by the sea for large distances and are commonly called " sea beans".

''Erythrina'' leaves are used as food plants by the larvae of some Lepidoptera species including the swift moth ''Endoclita damor'' and the woolly bears ''Hypercompe eridanus'' and '' Hypercompe icasia''. The mite ''Tydeus munsteri'' is a pest on the coastal coral tree ('' E. caffra'').

Many birds visit the nectar-rich ''Erythrina'' flowers. In the Neotropics, these are usually larger hummingbirds, for example the swallow-tailed hummingbird (''Eupetomena macroura'') and the black-throated (''Anthracothorax nigricollis'') and green-breasted mangos (''A. prevostii'') – though they seem not to be especially fond of '' E. speciosa'' at least, which they visit rather opportunistically. In Southeast Asia, the black drongo (''Dicrurus macrocercus'') which usually does not eat nectar in quantity has been observed feeding on '' E. suberosa'' flowers, and mynas and of course more specialized nectar feeders also utilize coral tree flowers. Lorikeets such as the collared lory (''Phigys solitarius'') and the possibly extinct New Caledonian lorikeet (''Charmosyna diadema'') are known to consume (or have consumed) large amounts of ''Erythrina'' nectar.

Use by humans

Some coral trees are used widely in the tropics and subtropics as street and park trees, especially in drier areas. In some places, such as Venezuela, ''bucaré''s are used as shade trees for coffee or cocoa crops. In the Bengal region, they are used for the same purpose in ''Schumannianthus dichotoma'' plantations. '' E. lanceolata'' in particular is considered highly suitable as "frame" tree for vanilla vines to grow up on.

Native Hawaiians made a number of items from ''wiliwili'' wood because of its low density, such as ''mouo'' (fishing net floats), ''ama'' (outrigger canoe floats, and extremely long ''papa hee nalu'' (surfboards) called ''olo''. ''Olo'', which averaged , were exclusively ridden by '' alii'' (royalty). The wood was sometimes used for the '' waa'' (hull) of outrigger canoes intended to be used near-shore, for recreation, or for training. The shiny orange-red seeds were strung into '' lei''.

The conspicuous, even dramatic coral trees are widely used as floral emblems. cockspur coral tree ('' E. crista-galli'') is the national flower of Argentina and Uruguay. The coastal coral tree ('' E. caffra'') is the official city tree of Los Angeles, California, where it is referred to simply as the "coral tree". The state trees of Mérida and Trujillo in Venezuela are ''bucaré ceibo'' ('' E. poeppigiana'') and purple coral tree (''bucaré anauco, E. fusca''), respectively. Yonabaru, Okinawa as well as the Okinawa Prefecture, Quanzhou, Fujian Province and Pathum Thani Province have the Indian coral tree ('' E. variegata'') as floral emblems. Known as ''thong lang'' in Thailand, the latter species is also one of the ''thong'' ("trees") referred to in the name of Amphoe Chom Thong, Chiang Mai Province. In a similar vein, Zumpahuacán in Mexico derives its name from Nahuatl ''tzompahuacá'', "place of the '' Erythrina americana''". In Vietnam, people use the leaves of ''E. variegata'' to wrap ''nem'' (a kind of fermented pork).

In Hinduism, the ''mandara'' tree in Indra's garden in Svarga is held to be '' E. stricta''. The same motif is found in Tibetan Buddhism, where the ''man da ra ba'' growing in Sukhavati is identified as an Indian coral tree (''E. variegata''). The concept of the Five Trees of Paradise is also found in Christian Gnosticism. Though as none of the trees is identified as an ''Erythrina'' here, the concept might not be as directly related to the Asian religions as some presume.

The seeds of at least one-third of the species contain potent erythrina alkaloids, and some of these are used for medicinal and other purposes by indigenous peoples. They are all toxic to some degree, however, and the seeds of some can cause fatal poisoning. The chemical compounds found in plants in this genus include alkaloids such as scoulerine, erysodin, erysovin (namely in '' E. flabelliformis''), and the putative anxiolytic erythravine (isolated from Mulungu, ''E. mulungu''). Erysodienone is a precursor in the biosynthesis of many of these alkaloids.

As food

Root tubers of ''Erythrina'' species have been traditional food for aborigines of the Northern Territory of Australia. NTFlora Northern Territory Flora online:
''Flora of the Darwin Region: Fabaceae.''
Retrieved 10 June 2018

Selected species

* '' Erythrina abyssinica'' Lam. ex DC. (East Africa)
* '' Erythrina acanthocarpa''
* '' Erythrina americana'' Mill. – ''Colorín'', ''Tzompāmitl'' (Mexico)
* ''Erythrina ankaranensis)
* ''Erythrina atitlanensis'' Krukoff & Barneby
* ''Erythrina berteroana'' Urb.
* ''Erythrina burana