Polygala myrtifolia

Sweet pea shrub

Family: Polygalaceae

Origin: South Africa

Sweet Pea shrub leaves and flower heads.
An evergreen perennial shrub from South Africa. Related to the pea family, the plant can fix nitrogen in the soil.
Photo credit: Jonathan Boow

Regional Pest Management Plan (RPMP) status

  • National Pest Plant Accord Species
  • Whole region — Sustained control

View more about the RPMP statuses

General description

Sweet pea shrub is here defined as all Polygala myrtifolia cultivars, except the cultivar ‘Grandiflora’. Evergreen perennial legume-like shrub < 2 m tall. Young stems are covered in short curly hairs. Stems are smooth, woody and many-branched.

Leaves are oval, smooth and alternate. Flowers are sweet pea-like and borne in January – December. Seed capsules are flat and heart-shaped. Seeds are dark brown and hairy.

What you need to know

To help protect our environment:

  • You must not breed, distribute, release or sell sweet pea shrub. As sweet pea shrub is a National Pest Plant Accord species, these restrictions apply within the Auckland region and across the whole of New Zealand.
  • You must not plant sweet pea shrub 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 sweet pea shrub 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.


Coastal areas, forest margins, scrubland, cliffs, open areas, tussocks.


Seeds dispersed by gravity, wind, water, possibly ants.

Impact on environment

Forms dense stands, displacing native vegetation, especially coastal shrub species.


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.


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 with 1g 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.

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

A mature Sweet Pea shrub with many flowers.
Flowers are bright pink and white and form at the tips of branches. Once flowers are pollinated they form into seed pods that are flat and heart shaped.
Photo credit: Jonathan Boow
Sweet Pea shrub growing amongst other plants.
A hardy plant that can grow in many places, it can form dense stands and outcompete native plants. Sweet pea shrub is particularly successful at growing in our coastal areas.
Photo credit: Jonathan Boow