Most species of the woody genus Erythrina have remarkable, large, tubular, pea-type flowers with tough petals in shades of red, orange or coral. The generic name is a reference to the red flowers of the American species Erythrina herbacea. There are more than 120 Erythrina species, and they are widely distributed through dry and monsoon regions in tropical and subtropical Asia, Australia, Africa and the Americas.
The appearance of the flowers indicates these trees are probably pollinated by birds, predominantly sunbirds and hummingbirds. Whilst feeding on the nectar, a bird’s feathers may become dusted with pollen, which will be carried to neighbouring flowers and trees as it continues to feed. Given their appearance, it is hardly surprising that Erythrina species have been woven into the art and folklore of many peoples living in the tropics and subtropics.
Originally from Central and South America, Erythrina crista-galli is grown outdoors in the Botanic Garden. This small tree will grow outside in the United Kingdom if coppiced and given winter protection. It flowers reliably, producing huge, bi-coloured, red-orange flowers that drip with nectar during warm summer weather. In warmer climates, Erythrina crista-galli is often grown as a street tree, providing welcome shade and spectacular displays.
Many members of the genus are used for their ornamental properties in tropical and subtropical regions. Some Erythrina species are used as shade trees for coffee and cocoa in the Americas. In Hawai’i, the wood of Erythrina sandwicensis was traditionally used for making royal surfboards.
Many Erythrina species are used in traditional medicines. Extracts from the leaves of Erythrina crista-galli produce a painkiller. Bark extracts from East African Erythrina abyssinica are used to treat conditions as diverse as snake bites and measles. Central American Erythrina berteroana is one of several species to produce hypnotic alkaloids, the highest concentrations of which are in the flowers and young shoots. In its native range, a sleep-inducing tea has been made from this species’ flowers since pre-Mayan times. Today, flowers are traded commercially to feed international markets. In 2005, under a Louisianan state law, the cultivation, possession and sale of the entire genus was banned, except for ornamental purposes. It had joined a list of plants with known or presumed hallucinogenic properties.
Thirteen Erythrina species are threatened globally, including the Madagascan endemic Erythrina ankaranensis, a species known from only six populations within the Ankarana National Park in the north of the country.
Neill, DA 1987. Trapliners in the Trees: Hummingbird Pollination of Erythrina Sect. Erythrina (Leguminosae: Papilionoideae). Annals of the Missouri Botanical Garden 74: 27-41.
Westley SB and Powell MH 1993. Erythrina in the New and Old Worlds. Editorial Paia.