Acanthus mollis

Bear's breeches

Also known as:

Bear's foot

Family: Acanthaceae

Origin: Europe, North Africa

Close up of a cluster of acanthus leaves.
Shades out small native plants in shady environments. It spread by water and birds, and it also spreads by root fragments.
Photo credit: Jonathan Boow

Regional Pest Management Plan (RPMP) status

  • Not a legally declared pest
  • Hauraki Gulf Controlled Area Notice pest

View more about the RPMP statuses

General description

Perennial herb < 120 cm tall. Roots are thick. Leaves are large, multi-lobed, shiny and borne on < 50 cm petioles from the root crown or < 2 cm petioles from the stem.

Flowers are white with pink/purple/brown veins and borne on a central spike in October-April. Seed capsules are 3-4 cm long, beaked and contain one flattened seed.

What you need to know

Although bear’s breeches is not a legally declared pest plant, it may still be invasive in some situations. Consider lower risk alternatives for your garden, such as native plants.

Habitats

Coastal areas, disturbed forest, riparian margins, wasteland, urban areas, roadsides.

Dispersal

Seeds dispersed by gravity and water. Vegetative spread from root fragments. Human-mediated dispersal through dumping of garden waste.

Impact on environment

Can form dense infestations and outcompete native plants. Allelopathic.

Control

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 and roots.

Disposal options: Remove to greenwaste or landfill.

Biocontrol

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: Foliar spray with 5g metsulfuron-methyl per 10L of water.

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

A large bush of the acanthus with tall flower stalks above it.
Flowers are red/pink and white.
Photo credit: Jonathan Boow
Acanthus spreading along a bank in bloom.
Spreads rapidly in disturbed ground, covering large areas.