- A native of the Mediterranean, Caltrop is now found throughout Queensland in disturbed areas, roadsides, agricultural land and native vegetation.
- Toxic to animals.
- Spreading, prostrate annual or biannual herb with purplish-brown branches and woody tap root.
- Numerous finely-hairy, stems up to 60 cm long, much branched.
- Leaves silky-hairy, green above and paler beneath, opposite and unequal in size, with 5-7 pairs of leaflets
- Yellow short-lived (1 day) flowers with 5petals to 10 mm long and carried singly on short stalk in leaf axils.
- Fruit is a woody burr, 6-12 mm across, composed of 5 wedge-shaped segments each with two large spreading and usually two short stout conical spines.
- Seed yellow, up to 4 seeds per segment of 20 seeds per burr.
- Spread by tyres and boots.
Currently not declared although its control is recommended.
Action For control information contact your local government weed inspector or your Biosecurity Queensland Land Protection Officer.