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Blue heliotrope (Heliotropium amplexicaule)

Blue heliotrope has rapidly expanded across large areas of south-eastern Queensland and northern New South Wales, where it competes with crops and pasture. It is drought tolerant and contains toxins that can reduce livestock performance or cause death.

Key facts

Type: Weed, herb.

Native to: South America: northern and central Argentina, southern Bolivia, Uruguay and the extreme south of Brazil.

Established in: QLD, NSW, ACT, VIC, SA.

Other names: Wild heliotrope, Clasping heliotrope, Creeping heliotrope, Wild verbena.

Best time to act: Look for seedlings in spring and summer, when cultivation can control them; flowering begins in late spring and continues until early autumn.

Identification

  • It is a perennial, spreading to prostrate herb that grows to a maximum height of 60 cm.
  • Mature plants have a stout, woody rootstock, and the stems are covered with glandular and non-glandular hairs.
  • The alternate leaves are dull green, hairy and soft to touch, up to 90 mm long and 25 mm wide.
  • Small tubular flowers, up to 6 mm across, are mauve to blue with a yellow centre and grow along one side of a coiled flower spike.
  • As the fruit matures, the spike uncoils; each fruit consists of two dark-brown, wrinkled, hairless nutlets.
  • Look-alike: Veined verbena (Verbena rigida) has coarse-textured, serrated leaves and lacks the coiled flower spike.
  • Look-alike: Mayne's pest (Glandularia aristigera, also called Verbena aristigera) has highly divided leaves and lacks the coiled flower spike.

Where it grows

In Australia it occurs in warm temperate, subtropical and sometimes semi-arid regions, growing in pastures, crops, fallows, roadsides, turf, disturbed sites and waste places.

Why it matters

  • It competes with desirable crop and pasture species, especially for moisture and nutrients after drought.
  • It is recognised as a problem in Queensland sugar cane crops.
  • It contains pyrrolizidine alkaloids that are toxic to livestock and can reduce animal performance or cause death.

How it spreads

  • It reproduces by seed and root fragments; seed can be spread by water, especially in riparian habitats and on steep terrain with erosion and runoff.
  • Contaminated soil and fodder, vehicles, and the fur and manure of livestock can transport seed.
  • Roadside maintenance disperses it, while cultivation and hand pulling can spread root fragments and encourage regeneration.

Control options

  • Registered herbicides can provide control, but those currently registered have had limited success and are not selective.
  • Cultivation can control seedlings in spring and summer, but may stimulate dormant seeds, spread root fragments and encourage regrowth from rootstocks.
  • On arable land, combine mechanical cultivation, herbicide application and good pasture management.
  • The leaf beetle Deuterocampta quadrijuga is an established biological control agent known to impact the weed; Longitarsus sp. has shown potential.

Hygiene and washdown

  • Seed can be transported in contaminated soil and fodder, on vehicles, and in livestock fur and manure; roadside maintenance can also disperse the plant.
  • 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: Regional priority in 2 of 11 regions. Regional priority weed in Central Tablelands, North Coast. 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: 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.

  • 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
  • Australian Capital Territory: Biosecurity Act 2023 (ACT), administered by ACT Biosecurity
  • 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