Ricinus communis

Castor oil plant

Family: Euphorbiaceae

Origin: Africa, Asia

The flowers and leaves of castor oil plant.
Spikes of flowers develop into spiny greenish capsules which split to release large, oval seeds.
Photo credit: Jonathan Boow

Regional Pest Management Plan (RPMP) status

  • Whole region — Sustained control
  • Hauraki Gulf Controlled Area Notice pest

View more about the RPMP statuses

General description

Suckering perennial shrub or small tree < 4 m tall. Stems are hollow, branching and hairless. Leaves are large, alternate, glossy green/red/purple/brown, palmate and serrated. Flowers are red/green and borne in inflorescences. Seed capsules are spherical, greenish and spiny.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell castor oil plant within the Auckland region.
  • You must not plant castor oil plant within the Auckland region, unless you are transferring an existing plant on your land to another location within the boundaries of the same property.
  • You must destroy any castor oil plant on land that you occupy if it has been planted in breach of the above rules and you are directed to do so by an authorised person.

Habitats

Open habitats, disturbed sites, wasteland, riparian margins, gardens.

Dispersal

Seeds dispersed by explosive dehiscence and water. Vegetative spread from adventitious shoots.

Impact on environment

May outcompete and prevent revegetation of plants in disturbed habitats, pasture and cleared forestry plantations. Extremely poisonous to humans, livestock, native fauna and pets. Strongly allergenic.

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.

Disposal options: Remove to greenwaste or landfill if practical.

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 double strength glyphosate gel or cut stump and spray freshly cut base with 200ml glyphosate green per 1L of water.

Certified Handler/Experienced agrichemical user: Foliar spray with 200ml glyphosate green per 10L of water and 20ml penetrant.

Safety notes

Extremely poisonous, especially seeds.

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

Castor oil plant with purple pointy leaves.
When the green seed capsule dries it splits into three sections, ejecting seeds.
Photo credit: Jonathan Boow
Castor oil plant with green leaves and red stalks.
Castor oil plant is a small, spreading tree up to 4m tall.
Photo credit: Jonathan Boow
Close up of a purple castor oil plant leaf with seven points.
The leaves are soft, large and have deep lobes.
Photo credit: Jonathan Boow