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Easter cassia (Senna pendula)

Cassia is an introduced, fast-growing shrub that invades bushland in eastern New South Wales, especially coastal areas. It can outcompete native plants and reduce food and habitat for native animals.

Key facts

Type: Weed, shrub.

Native to: Brazil and Paraguay.

Established in: QLD, NSW.

Other names: Senna.

Best time to act: Treat plants before they flower and set seed; flowers usually appear from late summer to autumn but may be present at any time of year.

Identification

  • A perennial spreading or sprawling shrub, usually 2–4 m tall, that can reach 5 m when supported by other plants.
  • Leaves alternate along the stems and have 3–6 pairs of opposite, dark-green leaflets with rounded tips and a lighter middle vein.
  • Bright-yellow, pea-like flowers about 3 cm wide grow in clusters at branch tips, usually from late summer to autumn but sometimes at other times.
  • Cylindrical pods hang downwards, turning from green to pale brown or straw-coloured as they mature; they are 10–20 cm long and contain 5–40 seeds.
  • Young stems are green and sparsely hairy; mature stems are woody, hairless and grey or brown.
  • Look-alike: Winter senna (Senna septemtrionalis) has leaflets with pointed rather than rounded tips.
  • Look-alike: Native coffee bush (Breynia oblongifolia) has alternate leaves and round berries.

Where it grows

In New South Wales, cassia grows along waterways, on roadsides and other disturbed sites, in woodlands and forests, on coastal hind-dunes, and in gardens and urban bushland, in full sun or shade and across a range of soils.

Why it matters

  • It invades bushland, particularly in coastal areas.
  • It can outcompete native plants.
  • It reduces food and habitat for native animals.

How it spreads

  • Plants begin producing fruit after 2–3 years, and each plant can produce over a thousand seeds per year.
  • Seeds can remain viable in the soil for over 5 years.
  • Seeds spread by water, in contaminated soil, and when people dump garden waste.

Control options

  • Pull or dig out small plants when the soil is damp or soft, removing the roots to prevent regrowth; mulching can suppress new growth.
  • For seedlings and plants less than 2 m tall, spot spray actively growing plants and cover all foliage; use herbicides only in accordance with the product label and any permit.
  • For tall plants or plants close to desirable vegetation, cut the stem low and apply herbicide within 15 seconds; collect any seed pods.
  • Follow up after initial control by checking for and killing regrowth and new seedlings; contact the local council weeds officer for technical advice and guidance on pod disposal.

Hygiene and washdown

  • Avoid moving soil that may contain cassia seeds.
  • Do not dump garden waste; collect seed pods and seek local council advice on disposal.
  • 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: 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

Sources