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Pannicle jointvetch (Ctenodon paniculatus)

Pannicle Jointvetch can form dense thickets that exclude useful pasture species, especially in woodland and rangeland areas. It is an agricultural sleeper weed identified as having potential for nationally significant impacts if it spreads.

Key facts

Type: Weed, shrub.

Native to: Tropical areas of the Americas.

Established in: QLD, NT.

Best time to act: Look for and treat plants during active growth before seed production in late summer, an opportunity generally limited to 2–3 months in the Australian monsoon tropics.

Identification

  • It is a leguminous subshrub or shrub, 1–2.5 m tall, with tough, spindly, reddish-brown grooved stems.
  • Its compound leaves are about 4–9 cm long, with 40–80 elliptic or oblong leaflets arranged along two sides of the leaf axis and no terminal leaflet.
  • The leaflets are sensitive to touch.
  • Numerous yellow, pea-shaped flowers are 6–7 mm long.
  • Its 15–22 mm-long pods have shallow indentations along the upper margin and deeper indentations along the lower margin, dividing each pod into 3–5 sections that break free at maturity.
  • Look-alike: Aeschynomene aspera also has leaflets with one main nerve, but its lower stems are spongy and its seed pods are more than 6 mm wide, with corky sections and rough margins.
  • Look-alike: Aeschynomene indica also has leaflets with one main nerve, but its plants are hairy and sometimes viscid, and its mature fruit sections are strongly ridged and wrinkled rather than smooth.

Where it grows

In Australia it is recorded in Queensland and the Northern Territory, including grasslands, dry Eucalyptus and Corymbia woodlands, and seasonally wet Melaleuca woodlands in Queensland.

Why it matters

  • It can develop into thickets that exclude useful pasture species.
  • It is reported to be more likely to affect woodland and rangeland pastures than cropping or agricultural areas.
  • In naturalised areas of Queensland it has spread rapidly, particularly where soil is exposed each dry season.
  • Without control, abundant seed can lead to near-pure stands developing over a few years.

How it spreads

  • It produces abundant, long-lived seed, but no particular method of spread has been established.
  • Seeds can pass through ruminants and establish in dung; in monsoonal areas, heavy rain is suspected of moving seeds downslope.
  • Vehicles may carry seeds embedded in mud.

Control options

  • Use registered herbicides during active growth, just before seeds are produced in late summer.
  • Grazing generally does not prevent seeding, although it can suppress grass cover and make plants easier to detect; vigorous pasture can slow establishment and spread.
  • Fire can cause mass germination, with more than 500 seedlings per square metre recorded in North Queensland, and can help deplete the soil seed bank if seedlings are treated soon afterwards with herbicide.
  • Eradication appears problematic, including because access to infestations can be difficult during the wet season.

Hygiene and washdown

  • Vehicles may carry seeds embedded in mud, so clean mud from vehicles before moving from infested 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: 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: 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: 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)
  • Northern Territory: Territory Parks and Wildlife Conservation Act 1976 (NT), administered by NT Department of Lands, Planning and Environment

Sources