Spiny broom is an invasive perennial shrub that can form dense areas, excluding and outcompeting native vegetation.

It can quickly take over farmland, reducing grazing and harming native ecosystems. Its seeds can survive in the soil for many years, so once it establishes, it can be hard to control. It also fixes nitrogen in the soil, which helps it grow in poor soils. 

There are three known sites for spiny broom — these are Chain Hills and Brighton, both in Dunedin, and Waihola

• Size: Up to three metres in height.
• Leaves: Dark or grey-green, about 12 millimetres long, with three leaflets that are hairy underneath and may occur in clusters. These plants also have ridged stems with sharp spines.
• Flowers/seeds: Bright yellow flowers and flattened, hairless seedpods.
• Root system: The plant has a tap root underground (a thick central root that grows straight down).
• Similar species: Spiny broom can be differentiated from broom by its sharp spines.
• Habitat: Includes rocky soils, grasslands, pastures, roadsides, forests, shrublands and cleared areas.

Flowering can occur between spring and summer (September–February). Barbs can be seen on the plant all year round.

To reduce the infestation of spiny broom in Otago and its negative environmental and economic effects, this plant pest is in the eradication programme of the Otago Regional Pest Management Plan (2019–2029).

Do not attempt to undertake control of spiny broom yourself. Report any sightings to Otago Regional Council.