Cassia (Senna pendula var. glabrata)

Also known as: senna, Easter cassia

Cassia is a tall sprawling shrub with bright yellow flowers. It invades bushland and outcompetes other plants.

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How does this weed affect you?

Cassia is fast growing and it:

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

What does it look like?

Cassia is a perennial spreading or sprawling shrub 2–4 m tall. If supported by other plants it can grow up to 5m. The stems are usually upright but lean over when laden with flowers or pods.

Leaves:

  • are up to 8 cm long on stalks up to 4 cm long
  • alternate along the stem
  • consist of 3-6 pairs of opposite leaflets.

Leaflets are:

  • dark green with a lighter-coloured middle vein
  • up to 5 cm long and 2.0 cm wide
  • egg to oval shaped with rounded tips (sometimes slightly indented)
  • almost hairless

There is a small cone-shaped gland between the lowest pair of leaflets of each leaf.

Flowers are:

  • bright yellow and pea-like
  • about 3 cm wide with 5 large petals
  • on stalks up to 2.5 cm long
  • in clusters at the tips of the branches
  • usually present from late summer to autumn but may be present any time of year.

Fruit are:

  • cylindrical pods that hang downwards
  • green when young and pale brown or straw coloured when mature
  • 10–20 cm[1]  long and 0.8 - 1.2 cm wide
  • filled with 5–40 seeds.

Seeds are:

  • brown
  • round and flattened
  • 4-6 mm in diameter.

Stems are:

  • multi-branched
  • green and sparsely hairy when young
  • hairless, woody and grey or brown when mature.

Roots are

  • woody
  • branched
  • usually shallow.

Similar looking plants

Cassia looks like:

  • Winter senna (Senna septemtrionalis), another invasive weed, which has leaflets with pointed, rather than rounded tips.
  • Coffee bush (Breynia oblongifolia), a native plant, which has alternate leaves and round berries.

Where is it found?

Cassia grows throughout eastern NSW. It is most common in coastal regions.

Cassia is native to Brazil and Paraguay.

What type of environment does it grow in?

Cassia prefers tropical, subtropical and warm temperate regions. Cassia can grow in a wide range of soils including sandy and salty conditions. It grows in full sun and shade.

It is frost tolerant and the base of the plant can reshoot if the upper parts are damaged by frost. Plants can also reshoot after fire.

 In NSW it grows:

  • along waterways
  • in disturbed sites such as roadsides
  • in woodlands and forests especially on the edges
  • in coastal hind- dunes
  • in gardens and urban bushland.

How does it spread?

By seed

Cassia plants start producing fruit after 2 - 3 years. Each plant can produce over a thousand seeds per year. The seeds can remain viable in the soil for over 5 years.

Seeds can spread by water, in contaminated soil and by people dumping garden waste.

Acknowledgements

2021 Edition: Plain language review Stephanie Alt: New content and editing by Wendy Gibney. Edited by Birgitte Verbeek. 

References

Identic Pty Ltd. and Lucid Central (2016). Environmental Weeds of Australia Fact sheet: Senna pendula (Willd.) Irwin & Barneby var. glabrata (Vogel) Irwin & Barneby. Retrieved 12 May 2021 from: https://keyserver.lucidcentral.org/weeds/data/media/Html/senna_pendula_var._glabrata.htm

Muyt, A. (2001). Bush invaders of South-East Australia: a guide to the identification and control of environmental weeds found in South-East Australia. RG and FJ Richardson.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved. Retrieved 12 May 2020 from https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=in&name=Senna~pendula~var.+glabrata

Randel, B. R. (1990). Revision of the Cassiinae in Australia. 1. Senna Miller Sect. Chamaefistula. Journal of the Adelaide Botanic Garden, 13, 1-16.

More information

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Control

Successful weed control requires follow up after the initial efforts. This means looking for and killing regrowth or new seedlings. Using a combination of control methods is usually more successful.

Control plants before they flower and set seed.

Physical removal

Pull or dig out small plants when soil is damp or soft. Dig out the roots so the plants do not reshoot. Mulching can suppress new growth.

Chemical control

Spot spray

Spot spraying is effective on seedlings and plants less than 2 m tall in dense infestations.

Cut stem

Taller or individual plants amongst other desirable plants can be cut and herbicide applied to the cut stem. If herbicide is not applied the cut stems it will regrow. If plants have seed pods collect and dispose of the pods.

Disposal

Dried seed pods can be burnt in a hot fire. Contact your local council for further advice on how to dispose of seed pods

Herbicide options

WARNING - ALWAYS READ THE LABEL
Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website www.apvma.gov.au

See Using herbicides for more information.


PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Various products)
Rate: 1 part per 1.5 parts of water
Comments: Stem injection/cut stump application.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Various products)
Rate: 200 mL glyphosate per 10 L water
Comments: Spot spray application.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L with Metsulfuron-methyl 600 g/kg (Various products)
Rate: 200 mL glyphosate plus 1.5 g metsulfuron-methyl per 10 L water
Comments: Spot spray application.
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate


PERMIT 9907 Expires 31/03/2025
Metsulfuron-methyl 600 g/kg (Various products)
Rate: 1.0–2.0 g metsulfuron-methyl per 10 L water
Comments: Spot spray application.
Withholding period: Nil (recommended not to graze for 7 days before treatment and for 7 days after treatment to allow adequate chemical uptake in target weeds).
Herbicide group: B, Inhibitors of acetolactate synthase (ALS inhibitors)
Resistance risk: High


Picloram 44.7 g/L + Aminopyralid 4.47 g/L (Vigilant II ®)
Rate: Undiluted
Comments: Cut stump application. Apply a 3–5 mm layer of gel for stems less than 20 mm. Apply 5 mm layer on stems above 20 mm .
Withholding period: Nil.
Herbicide group: I, Disruptors of plant cell growth (synthetic auxins)
Resistance risk: Moderate


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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW DPI Biosecurity Helpline on 1800 680 244 or send an email to weeds@dpi.nsw.gov.au

Reviewed 2021