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One-leaf Cape tulip (Moraea flaccida)

One-leaf Cape Tulip is an introduced garden escapee and a significant weed across southern Australia. It can invade pastures, reduce their carrying capacity through selective grazing, and is highly toxic to grazing animals.

Key facts

Type: Weed, herb.

Native to: South Africa, particularly the Cape of Good Hope.

Established in: NSW, VIC, TAS, SA, WA.

Other names: Cape Tulip.

Best time to act: Plants emerge after autumn rains, flower in September, and are most effectively treated with herbicide just before or as flowering begins; the corm transition stage for cultivation usually occurs in June or July.

Identification

  • This perennial herb grows from a white underground corm covered in a brown, fibrous tunic, and its flowering stems can reach 60 cm high.
  • Each plant has one flat, folded and ribbed leaf, usually 1–2 cm wide and up to 1 m long, which may droop or trail on the ground.
  • Salmon-pink, orange or yellow flowers, 3–5 cm across, grow on an erect, somewhat zig-zagged stem.
  • The fruit is a narrow, cylindrical capsule that turns brown when mature and can contain up to 150 irregular brown seeds.
  • Look-alike: Two-leaf Cape Tulip (Moraea miniata) has two or three leaves and produces small bulbils in the leaf forks; it does not produce seed and has relatively broad petals.
  • Look-alike: Cape Tulip (Moraea ochroleuca) is less common and has yellow, rarely orange, flowers with relatively broad petals.

Where it grows

In Australia it is widespread across the south, especially south-west Western Australia, and occurs in pastures, disturbed areas and native vegetation, including dry coastal and woodland habitats.

Why it matters

  • All parts are toxic to grazing animals, with cattle generally more susceptible than sheep or horses.
  • Poisoning can cause loss of appetite, weakness, depression, blindness, dysentery, scouring and hind-leg paralysis; death usually occurs within three days.
  • Selective grazing can allow Cape Tulip to replace desirable pasture species and reduce carrying capacity, and in some parts of Western Australia infestations have led farmers to stop running stock.
  • It can impede the growth and regeneration of native ground flora and has potential to be a weed of conservation importance.

How it spreads

  • Seeds and corms spread in contaminated farm produce and machinery, while seeds can adhere to wool and animals’ feet.
  • Moving hay or silage cut from infested paddocks is an important cause of new infestations.
  • Seeds can remain viable after passing through stock, and dried plants with intact capsules can be blown by wind or carried in waterways.

Control options

  • Use a carefully planned, integrated program over several years, prioritising early treatment of new infestations and small patches.
  • Cultivate during the corm transition stage, usually in June or July, to at least 15 cm or the depth of the deepest corm; repeat after four weeks and as needed for at least four years, and dig isolated plants and destroy their corms and fruit by burning or immersion in boiling water.
  • Registered herbicide treatment can be effective when repeated annually over several seasons, timed just before or as flowering begins; consult the APVMA for chemical information.

Hygiene and washdown

  • Do not buy hay containing One-leaf Cape Tulip, and avoid moving hay or silage from infested paddocks.
  • Wash machinery after work in affected areas and before moving it to uninfested areas.
  • 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 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.
  • South Australia: Declared plant. Depending on the declaration, it can be an offence to move it on public roads or sell it, and landowners may be required to control it on their land.
  • Western Australia: Declared pest (no control category). Declared pest in WA without a control category, so there is no state-wide control requirement, but movement and keeping rules can still apply.
  • 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.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources