Biosecurity Spotters logo

Garden geranium (Pelargonium alchemilloides)

Introduced as a garden plant, garden geranium is currently naturalised at one small site in south-western Western Australia. It has invaded indigenous bushland and could threaten understorey plants, associated fauna and agricultural production across a wider area of southern Australia.

Key facts

Type: Weed, herb.

Native to: Southern Africa, extending north through tropical Africa to Ethiopia and Somalia.

Established in: .

Other names: Pelargonium, Lady’s Mantle-leaved Pelargonium, Pink Trailing Pelargonium, Wilde Malva.

Best time to act: The main flowering period is spring after the April–August regrowth period, although flowers may occur throughout the year.

Identification

  • It is a straggling, long-lived perennial herb, usually about 200 mm tall, with spreading stems from a woody tuberous or stoloniferous rootstock.
  • The stems have long, coarse hairs and grow from a central rosette of leaves.
  • Leaves are 2–7 cm across, with five to seven lobes cut at least halfway to the base; their irregularly toothed edges and dense hairs give them a silky appearance.
  • Some leaves have a purple, brown or dark red horseshoe-shaped zone.
  • Flowers grow in clusters of three to six, sometimes up to 15, and are usually white, cream or pink; the fruit is a distinctive crane’s-bill-shaped pod.

Where it grows

In Australia it is known from a roadside site about 2 km east of Hamelin Bay in south-western Western Australia, where it has invaded adjacent low peppermint woodland on sandy coastal soil.

Why it matters

  • At Hamelin Bay it has invaded intact indigenous vegetation and threatens to outcompete understorey plants and associated fauna.
  • It is considered capable of causing similar environmental impacts over a considerable area of southern Australia.
  • It may also affect agricultural production because it can colonise disturbed sites, produce abundant seed and survive harsh conditions.

How it spreads

  • It produces abundant seed and can also spread from stem and tuber cuttings.
  • Its tuberous rootstock helps it survive harsh dry periods, while seeds can remain viable in the soil seedbank for a long time.
  • Soil disturbance can prompt seed germination and growth from underground stem pieces; disturbance associated with roadworks was linked to increased numbers at Hamelin Bay.

Control options

  • Report any newly discovered infestations to the relevant state or territory weed management agency.
  • Lodge specimens with the relevant state or territory herbarium for formal identification.
  • For chemical information, consult the Australian Pesticides and Veterinary Medicines Authority.

Hygiene and washdown

  • Soil disturbance has been associated with increased numbers at Hamelin Bay; seeds can germinate and underground stem pieces can grow into new plants when soil is disturbed.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): National Environmental Alert List. One of 28 weeds named on the National Environmental Alert List as early-stage invaders with serious potential to harm the environment.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • Victoria: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

Sources