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Common sensitive plant (Mimosa pudica)

Common sensitive plant can be troublesome in crops and pastures, and is abundant and aggressive in high-rainfall areas. It is suspected of poisoning cattle, while its prickles can cause painful wounds and restrict grazing.

Key facts

Type: Weed, herb.

Native to: Tropical Central and South America.

Established in: QLD, NSW, NT.

Other names: Sensitive plant, Sensitive weed, Mimosa, Touch-Me-Not.

Identification

  • It is a prickly, creeping or sprawling long-lived herb or small shrub, usually 15 to 50 cm tall but sometimes reaching 1 m when supported by other vegetation.
  • Its reddish-brown to purplish stems become woody with age and bear scattered curved prickles.
  • The compound leaves have many small, dark-green leaflets that fold when touched and at night.
  • Pink or purplish-pink flowers form fluffy, round clusters, followed by flattened pods with stiff bristles along their edges.
  • Look-alike: Mimosa (Mimosa pigra) is a large upright shrub with 6 to 16 pairs of leaf branchlets and larger pods, 3 to 8 cm long; Giant Sensitive Plant (Mimosa diplotricha var. diplotricha) is upright or climbing, with 4 to 9 pairs of branchlets and pods 1 to 3.5 cm long.
  • Look-alike: Native Sensitive Plant (Neptunia gracilis) has yellow flowers and no stem prickles, and its pods do not split into one-seeded segments when mature.

Where it grows

In Australia it occurs in wetter coastal areas, especially northern and central Queensland, and is also present in south-eastern Queensland, New South Wales and the Northern Territory.

Why it matters

  • It can be a weed in pastures and is suspected of poisoning cattle.
  • Its thorns can cause painful wounds.
  • High plant populations and thorns can restrict grazing in tropical pastures.
  • It is troublesome in several crops and abundant and aggressive in high-rainfall areas.

How it spreads

  • Pods attach to wool, fur and clothing, allowing them to travel long distances with animals or people.
  • The one-seeded pod segments move easily in water.
  • Seed can also be moved in contaminated sand and gravel used in building and roadwork.

Control options

  • Chemical control can be used; consult the Australian Pesticides and Veterinary Medicines Authority for chemical information and use registered herbicides according to their directions.
  • Avoid disturbing plants before spraying, because the leaves fold and the herbicide may be ineffective.

Hygiene and washdown

  • Check clothing and gear for bristly pods, which can attach to clothing and be carried long distances.
  • Avoid moving sand or gravel contaminated with seed during building or roadwork.
  • 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): No national listing. Managed under state and territory law.
  • 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: Declared pest (C2), prohibited. C2 Eradication: present in limited areas and targeted for eradication. It must not be brought into WA (prohibited organism).
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Declared weed, Class B. Class B: growth and spread must be controlled. All declared weeds are also Class C, so they must not be brought into the NT.
  • 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.

  • Queensland: Biosecurity Act 2014 (Qld), administered by Biosecurity Queensland (13 25 23)
  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources