Caesalpinia decapetala

Mysore thorn

Family: Fabaceae

Origin: Asia

Mysore Thorn branches and flower stems.
A plant that can grow as a vine or as a shrub. The main stems are prickly and can catch on your clothing.
Photo credit: Forest and Kim Starr

Regional Pest Management Plan (RPMP) status

  • Unwanted organism

View more about the RPMP statuses

General description

Sprawling shrub or climber. Stems are thorny. Leaves are bipinnately compound, with 4-10 pinnae pairs each bearing 8-12 leaflets, pale undersides and a prickly main stalk. Flowers are yellow and borne in erect, elongated clusters. Seed pods are dark brown, < 11 cm long and dehiscent.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell mysore thorn. As mysore thorn is an Unwanted Organism, these restrictions apply within the Auckland region and across the whole of New Zealand.


Disturbed forest, forest and riparian margins, grassland, disturbed sites, pasture, plantations, gardens, roadsides.


Seeds dispersed by water, birds, small mammals and livestock. Human-mediated dispersal through dumping of garden waste and deliberate plantings.

Impact on environment

Forms dense thickets, smothering native vegetation and impeding movement of humans and animals.


Site Management

Follow up treated areas 3 times per year. Encourage natural regeneration of native plants or replant treated areas where possible after 2-3 treatments to establish dense ground cover and minimise reinvasion.

Recommended approaches

Physical control

Method: Dig out.

Plant parts requiring disposal: Seeds.

Disposal options: Remove to greenwaste or landfill if practical.


Biocontrol is currently not available for this species.

Community agrichemical control recommendations

No qualifications: Cut stump and paste freshly cut base of stems with metsulfuron gel.

Basic Growsafe certified: Cut stump and spray freshly cut base of stems with 2g metsulfuron-methyl per 1 L of water.

Certified Handler/Experienced agrichemical user: Foliar spray with 5g metsulfuron-methyl per 10L of water and 20ml penetrant.

Safety notes

Plant has thorns.

Caution: When using any herbicide or pesticide please read the label thoroughly to ensure that all instructions and safety requirements are followed.

Close up of Mysore Thorn flowers.
Yellow flowers are produced in long erect clusters above the branches. Seeds are held in pods that turn brown across summer.
Photo credit: Forest and Kim Starr
Underside of Mysore Thorn leaves with sky in background.
Leaves look similar to acacia leaves and create a dappled light effect on sunny days. Originating from Asia, this plant forms dense thickets outcompeting native plants.
Photo credit: Forest and Kim Starr