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Native to Mexico and Central America, physic nut is a perennial shrub with small yellow to green flowers.
Introduced to northern Australia in the late 1880s as a hedge and ornamental plant, it is now found in the Northern Territory and along the Queensland coast. In some parts of the world, oil from physic nut seeds is used in the production of biodiesel. However, in Queensland, physic nut is regarded as a weed because of its potential to invade savanna lands and compete with pasture.
Physic nut is not a prohibited or restricted invasive plant under the Biosecurity Act 2014.
- Barbados nut, Barbados purging nut, curcas bean
- Perennial shrub or small tree up to 6m tall.
- Leaves are alternate, palmate-shaped, 12.5-18cm long.
- Flowers are small, yellow to green.
- Fruit is ellipsoid capsule 2.5-3cm long, 2-3cm in diameter, initially yellow then turning black.
- Seeds are smooth, brown or black with fine yellow stripes, about 1.7cm long.
- Found in seasonally dry tropical savannas and thorn forests.
- Can grow on harsh dry sites, tolerates drought, withstands light frost.
- Found along Queensland coast.
- Germinates October-December.
- Flowers year-round.
- Has potential to invade seasonally dry tropical savannas.
- May be alternative host for some plant pests.
- Competes with pasture.
- Contains toxic compounds and is risk to human health if ingested.
How it is spread
- Seeds spread by water or in mud sticking to animals and vehicles.
- Herbicides for bellyache bush that are being used and/or investigated may also be effective on physic nut.
- No known biological controls.
- Physic nut is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, everyone has a general biosecurity obligation (GBO) to take reasonable and practical steps to minimise the risks associated with invasive plants and animals under their control.
- Local governments must have a biosecurity plan that covers invasive plants and animals in their area. This plan may include actions to be taken on certain species. Some of these actions may be required under local laws. Contact your local government for more information.
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- Last reviewed: 30 Jan 2020
- Last updated: 30 Jan 2020