Alternative common names:
Purgeerboontjie (Afrikaans), Barbados nut, purging nut.
This deciduous shrub or small tree grows 2-6m high and has light brown to grey-green bark. The physic nut is not a particularly aggressive weed and tends to spread relatively slowly. However, it is drought resistant and will grow under a wide range of climatic and soil conditions. The fresh seeds are highly poisonous to humans, especially to children, and can be mistaken for peanuts.
Where does this species come from?Mexico and Central America.
What is its invasive status in South Africa?NEMBA Category 2
Where in South Africa is it a problem?Limpopo.
How does it spread?Seeds are spread short distances when they are explosively released, while most long range dispersal probably occurs in water or in mud adhering to animals and vehicles. The spread of this species is also aided by its deliberate cultivation in home gardens.
Why is it a problem?
It has the potential to compete with and replace indigenous pioneering species, especially in watercourses, and it is extremely poisonous.
What does it look like?
Leaves: Leaves are alternate, green, ovate with three to five shallow lobes. The blade is 50-150mm long and wide, the petiole up to 200mm long.
Flowers: It has yellow-green flowers. The inflorescence is formed in the leaf axel. Male and female flowers are produced on the same inflorescence, averaging 20 male flowers to each female flower. Flowers appear from October to December.
Fruit/seeds: Capsule- Green turning brown, c. 25 x 30 mm, slightly 3 lobed, splitting to release 3 blackish seeds c. 20 mm long
Does the plant have any uses?
Extracts are used for various medicinal purposes, the seeds are used as a purgative and the bark as a fish poison. Oil from the seeds can be used as a biofuel.