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Spiny broom (Calicotome spinosa)

Spiny broom is an introduced shrub that has become established in a few higher-rainfall parts of Victoria after being grown as a garden or hedge plant. Its rigid spines can make infestations difficult to access, and it is identified as a noxious weed in Victoria.

Key facts

Type: Weed, shrub.

Native to: Mediterranean region.

Established in: VIC.

Other names: Thorny broom.

Best time to act: Survey when the yellow flowers are conspicuous, mainly November–December, and control plants before their pods mature.

Identification

  • An erect, well-branched shrub that can grow to about 3 m tall, with hairless stems bearing rigid spines.
  • Leaves have three small leaflets, usually 5–10 mm long; the middle leaflet is largest, and the undersides are sparsely hairy.
  • Yellow flowers, about 12–15 mm long, grow in clusters of 1–5 near the ends of branches, mainly in November and December.
  • Pods are narrow and oblong, 25–40 mm long, hairless, winged along the lower edge and tipped with a spine.
  • Each pod contains 5–15 compressed, shiny brown seeds.
  • Look-alike: It may be confused with other yellow-flowered broom shrubs, including Montpellier broom; look for spiny stems and the small three-leaflet leaves to distinguish spiny broom.

Where it grows

In Victoria it is established in a few higher-rainfall areas, including sites where it has escaped from gardens or hedges.

Why it matters

  • The stiff, sharp spines can make infested areas difficult and hazardous to walk through or work in.
  • Established shrubs can occupy space and compete with other vegetation.
  • Its presence can impede access for land management and maintenance work.

How it spreads

  • Spiny broom reproduces by seed contained in its pods.
  • Seed-bearing plant material or contaminated soil can be moved by people, vehicles and machinery, helping spread it to new sites.

Control options

  • For small plants, hand-pull or dig them out when the soil is moist, removing the roots; wear sturdy gloves and protective clothing to avoid the spines.
  • For larger shrubs, use a suitable physical or herbicide treatment, such as cut-and-paint or spot treatment with a herbicide registered for the situation, and follow the product label and local requirements.
  • Remove and dispose of seed-bearing material so pods and seeds are not carried to other sites.
  • Check treated areas for regrowth and new seedlings, and follow up as needed; check current requirements with Agriculture Victoria, as spiny broom is identified as a noxious weed in Victoria.

Hygiene and washdown

  • Before leaving an infested site, remove soil and plant material from vehicles, machinery, boots and tools.
  • Contain and dispose of seed-bearing cuttings carefully so pods or seeds are not transported elsewhere.
  • 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: Regionally prohibited / regionally controlled / restricted weed (varies by region). Where it is regionally prohibited, landowners must take all reasonable steps to eradicate it on their land. Where it is regionally controlled, landowners must take all reasonable steps to prevent its growth and spread on their land. Where it is a restricted weed, trade in it (including the plant, its seed or contaminated material) is prohibited.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • 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.

  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria

Sources