Botany
Sophora toromiro is considered a large shrub or small tree, with an adult height of up to 5 metres. Its leaves are pinnate, with bright yellow flowers. The flowers are hermaphrodite and 1.5-3.0 cm long. The wood is dense and hard, with a red-brown color and vertical fissures. Its fruits are elongated legume pods that contain several seeds. It belongs to the Edwardsia section, which is composed of over 20 species distributed in the South Pacific. It is in the same genus as kōwhai. Sophora is a genus of about 45 species of small trees and shrubs in the pea family Fabaceae. The trunk is twisted and carries several branches, and the bark is reddish-brown and fissured lengthwise.
Range
Sophora toromiro is endemic to Rapa Nui (Easter Island), a special territory of Chile annexed in 1888. The island lies 3,765 km west of continental Chile.
Cultural Use
The tree holds significant cultural importance for the Rapa Nui people, who made statues, ceremonial objects and other tools from the wood. Archaeological evidence shows that it was used as firewood and as raw material for the manufacture of ritual objects. Local tradition holds that the rongorongo tablets of Easter Island are made of toromiro. However, all tablets of native wood tested by modern methods have turned out to be Thespesia populnea.
Decline and Conservation
The population declined through overgrazing after the introduction of rabbits, sheep, pigs, horses and cattle. Other human impacts include increased use of fire for clearing as a basis for settlement. Seed collections carried out during the 1950s allowed the species to persist ex situ. Thor Heyerdahl collected seeds in 1956 and donated them to the Botanic Garden of Göteborg. The surviving plants arose through self-pollination and are classed in around 13 lines, kept in botanic gardens and private collections mainly in Europe and Chile. Conservation efforts to re-introduce seedlings to the island in the 1980s failed. The species has low genetic diversity, which makes reintroduction and conservation difficult. Reintroduction efforts now focus on the nitrogen-fixing symbiont in the root nodules common to legumes. A plant specimen with a handwritten date of 1800 had been misidentified; it was an Easter Island toromiro.
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