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Kahili ginger (Hedychium gardnerianum)

In Australia it has been planted as an ornamental and is reported as a weed of bushland, roadsides and riverbanks; its spread was flagged for pre-emptive eradication in Queensland. It forms dense rhizome mats and thickets that suppress the regeneration of other plants, so early detection and control matter.

Key facts

Type: Weed, herb.

Native to: Eastern Himalayas, including India, Nepal, Sikkim and the Khasia Hills.

Established in: QLD, NSW, VIC, SA.

Other names: yellow ginger lily, ginger lily, garland flower, wild ginger.

Identification

  • A perennial herb with leafy shoots about 1 to 2 m tall.
  • Large branching rhizomes grow at the surface and can form dense mats up to 1 m thick.
  • Leaves are alternate, oval to elliptic, about 25 to 45 cm long and 10 to 15 cm wide.
  • Scented, bright yellow flowers grow on upright spikes about 25 to 40 cm long.
  • After flowering, the spikes bear fleshy orange fruits containing shiny red seeds.
  • Look-alike: Hedychium coccineum has red or reddish-orange flowers and more slender, upright leaves.
  • Look-alike: Hedychium coronarium has sweetly fragrant white flowers; Hedychium flavescens has narrower leaves and smaller spikes with creamy-white to pale-yellow flowers.

Where it grows

In Australia it is reported as a weed of bushland, roadsides and riverbanks, and it has been recorded near Sydney and in Queensland.

Why it matters

  • Dense rhizome beds and thickets prevent seedlings of other plants from growing through and can displace lower-tier native plants.
  • Its shade tolerance and rapid growth allow it to invade forest understoreys and other moist, shaded sites.

How it spreads

  • It produces many seeds, which can be eaten and dispersed by birds and rats over short or long distances.
  • Rhizomes can spread as fragments, including when moved by water, soil, flooding, dumped vegetation or contaminated machinery.
  • It can also spread through deliberate planting as an ornamental.

Control options

  • Hand-pull young seedlings; for small populations, dig out the plants and remove all underground parts.
  • Cutting before flowering can reduce seed production. Cutting off the inflorescences before seeds form stops seeding but does not kill the plant.
  • For larger infestations, use registered herbicides where permitted and follow the product label; stump treatment after cutting is described as an effective approach.
  • Repeated cutting may slow propagation and spread but does not provide long-term control.

Hygiene and washdown

  • Avoid moving soil, rhizome fragments or dumped vegetation from infested sites.
  • Clean machinery and equipment before leaving infested areas, as contaminated machinery can spread fragments.
  • 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: Restricted matter, category 3. Do not give it away, sell or release it into the environment. 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.

  • 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
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board

Sources