Jatropha curcas
The species is a tree which, if left to grow, would reach about three metres tall. However, under cultivation, it is kept pruned to encourage branching and facilitate harvesting.
The tree grows wild throughout tropical Asia and the seeds contain 30-40% of oil which has been used for centuries by villagers for lighting and soap making. It is believed to have been introduced to the region from Central America by Portuguese sailors in the sixteenth century.
It is planted at approximately two thousand trees per hectare. Within three months of planting, the first flowers appear and a small crop is obtained in the first year. Full production is attained in the third or fourth after planting. The tree continues to fruit for up to forty years.
The fruits grow in bunches and within a bunch, ripening occurs unevenly. The fruit is best picked as it turns orange in colour, and if left to dry, turns black and the husks dry hard. Within are three seeds usually, black in colour and oily to the touch when fresh.
After harvest, the trees are usually pruned to encourage vigorous branching, and to keep the next harvest at easy picking height.
The species is tolerant of drought but yields well only under good rainfall conditions. It is also tolerant of poor soils, although like all plants requires an adequate supply of mineral nutrients to thrive.