Quick Facts

Quick facts

• Physic Nut (Jatropha curcas) is an upright shrub or small tree usually growing 2 to 4 m tall.
• Its fleshy capsules contain seeds that are very poisonous to humans and livestock.
• Physic Nut was has been widely grown around mining sites and homesteads in the northern parts of Australia.
• It has escaped cultivation, but tends to spread slowly, and only scattered infestations are currently present in northern Australia.
• Physic Nut can eventually form dense colonies and may threaten the biodiversity of some of Australia's rangeland communities in the future.

What Does It Look Like?

What is it?

Physic Nut (Jatropha curcas) is an upright shrub or small tree usually growing 2 to 4 m tall. The stems are thick and softly woody, with the younger ones sometimes being slightly hairy. The dark green leaves are relatively large (10 to 15 cm long and 5 to 15 cm wide) and shiny in appearance. They are alternately arranged along the stems and borne on stalks 6 to 13 cm long. These leaves have heart-shaped bases and 3 or 5 shallow rounded lobes (Navie 2004).

The pale yellow to greenish-coloured flowers are small and inconspicuous. They are borne in loose clusters on short stalks in the forks of the upper leaves. The fruit is a fleshy capsule that is initially green in colour, but turns yellow and then dark brown as it matures. These fruit are oval or almost round in shape (3 to 4 cm long) and usually contain three large seeds. The smooth textured seeds (17 to 20 mm long) are mostly brown or black in colour, with some fine yellow stripes. They are hard and slightly kidney-shaped (Navie 2004).

For further information and assistance with identification of Physic Nut contact the herbarium in your state or territory.

Flower colour

Yellow

Growth form (weed type/habit)

Shrub, Tree

Where it currently grows? Preferred habitat

Physic Nut is a weed of tropical and subtropical environments that is mainly found in disturbed sites, waste areas, abandoned gardens, pastures, open woodlands and along roadsides (Navie 2004).

Are there similar species?

Physic Nut is very similar to Bellyache Bush (Jatropha gossypifolia) and relatively similar to Castor Oil Plant (Ricinus communis). Bellyache Bush leaves are reddish in colour and covered in sticky hairs when young and its flowers have bright or dark red petals. Castor Oil Plant can be distinguished by having 7 to 9 lobes on its leaves and by the numerous soft, blunt spines on its fruiting capsules (Navie 2004).

Why Is It A Weed?

What are its impacts?

The fresh seeds of Physic Nut are highly poisonous to humans, especially to children and can be mistaken for peanuts (Shepherd 2004). They are also toxic to livestock, though few instances of stock poisoning have been reported in Australia (Parsons & Cuthbertson 2001).

Physic Nut is not a particularly aggressive weed and tends to spread relatively slowly. Plants are usually found in disturbed areas, especially around abandoned homesteads and mines. However, it is drought resistant and will grow under a wide range of climatic and soil conditions (Crothers 1998). Physic Nut competes with native species or pasture plants and can eventually form dense thickets or colonies (Smith 2002).

If it is allowed to establish widespread populations over time, it may threaten some of Australia's rangeland communities. For example, it is regarded as posing a threat to biodiversity in the Einasleigh and Desert Uplands bioregion in inland northern Queensland (Grice & Martin 2005).

Physic Nut may also act as an alternative host for insect pests of cotton crops (Parsons & Cuthbertson 2001).

How does it spread?

Physic Nut reproduces mainly by seed, though some suckering can occur from its tuberous roots and damaged crowns. The seeds can be dispersed short distances when the ripe capsules split open and explosively release their seeds. They are then spread larger distances in water flows or in mud adhering to animals and vehicles. (Parsons & Cuthbertson 2001). The spread of this species is also aided by its deliberate cultivation in home gardens (Smith 2002).

What is its history in Australia?

Physic Nut was deliberately introduced into the Northern Territory at some time in the late 1800s. It was mainly grown as a hedging plant or garden ornamental around mining sites and homesteads in the northern parts of Australia (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Single Physic Nut plants should be dug out and burnt, taking care to remove as much of the tuberous root system as possible (Crothers 1998).

Larger colonies can be controlled with herbicides, preferably using the cut-stump method (i.e. cut the plant off close to the soil surface and immediately swab the cut surface with herbicide). Herbicides can also be effective when applied using basal bark, soil injection and foliar application methods (Parsons & Cuthbertson 2001). Also see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au .

Physic Nut has also been recognised as a target for biological control through a cross-jurisdictional government process. This allows activities to be undertaken to develop effective biological controls.

Check with your local council or state/territory government agency about its requirements for the control of Physic Nut.

Does it have a biological control agent?

YES

When does it grow? (lifecycle/growth calendar)

The seeds germinate at the onset of the wet season in northern Australia (i.e., usually between October and December). Growth is relatively rapid during the wet season and slows during the dry season, unless the plant is growing near a permanent waterway or other water source (Parsons & Cuthbertson 2001). Flowering can occur throughout the year (Parsons & Cuthbertson 2001), but is most abundant during the wet season (Solomon Raju & Ezradanam 2002).

Where Is It Found?

Which states and territories is it found?

• NT
• QLD

What areas within states and territories is it found?

Physic Nut has a scattered distribution throughout the coastal and sub-coastal districts of northern and north-eastern Australia. It is most common in the north-western parts of the Northern Territory (particularly around Darwin) and in northern Queensland. It is occasionally also found in the coastal regions of central and southern Queensland and is present in the inland regions of the Northern Territory (Navie 2004). The two main infestations in the Northern Territory are located near Pine Creek and Kapalga (Smith 2002).

Where does it originate?

Physic Nut is native to Mexico, the Caribbean, Central America (i.e., Belize, Costa Rica, El Salvador, Guatemala, Honduras and Nicaragua) and South America (i.e., Brazil, Bolivia, Peru, Argentina and Paraguay) (GRIN 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

WA, NT

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Jatropha curcas

Other scientific names (synonyms)?

Manihot curcas (L.) Crantz

Does it have other known common name(s)?

• Physic Nut
• Purging Nut
• Purging Nut Tree
• Cuban Physic Nut
• Barbados Nut
• Barbados Purging Nut