Quick Facts

Quick facts

  • Hairy Senna (Senna hirsuta) is a soft woody perennial shrub, growing to 0.5–3 m tall, with hairy leaves and pods.
  • It invades and completely dominates pastures.
  • Once established, it remains a problem for years, as seed remains viable for 10 years in the soil.
  • Prevention is the best control method, but physical and chemical control is also useful.

What Does It Look Like?

What is it?

Hairy Senna (Senna hirsuta) is a large upright herb or small shrub growing to 0.5–3 m tall. The stems, leaves and seed pods are all densely covered with long greyish-white hairs. Leaves are stalked and consist of three to six pairs of large leaflets up to 105 by 40 mm in size. These leaflets have pointed tips, and the leaf stalks bear a small finger-like gland.

The yellow to deep orange-yellow flowers have five petals 8–15 mm long and they are borne in small clusters in the leaf forks. These clusters usually contain 2–8 flowers and their petals may become conspicuously brown-veined as they mature.

The fruit is a very slender, flattened pod, 10-18 cm long, that is usually curved downwards. These pods are densely covered in long whitish hairs and turn brown as they mature (Navie 2004). For further information and assistance with identification of Hairy Senna contact the herbarium in your state or territory.

Flower colour

Yellow, Orange

Growth form (weed type/habit)

Shrub, Herb

Where it currently grows? Preferred habitat

Hairy Senna is a potential weed of disturbed sites, waste areas, roadsides, waterways, plantation crops, forest margins, open woodlands, pastures, grasslands and coastal environs in tropical and sub-tropical regions. In Asia, Hairy Senna grows on plains and hilly areas and spontaneously in waste locations, along roadsides, railway embankments, dry ditches and in secondary forest. It is found in gardens and fields as a weed, and prefers open locations (Navie 2004; ICRAF undated).

Are there similar species?

Hairy Senna is very similar to Sicklepod (Senna obtusifolia), Java Bean (S. tora), Coffee Senna (S. occidentalis), Smooth Senna (S. septemtrionalis) and the native Arsenic Bush (S. planitiicola). It is also relatively similar to Easter Cassia (S. pendula var. glabrata), Pepper-leaved Senna (S. barclayana), Candle Bush (S. alata), Popcorn Senna (S. didymobotrya) and Sesbania Pea (Sesbania cannabina var. cannabina). Hairy Senna can be distinguished from all these species by the long greyish-white hairs that cover the stems, leaves and pods. The leaflets of Hairy, Coffee, Smooth and Pepper-leaved Sennas, as well as Arsenic Bush, have pointed tips, while those of the remaining species are rounded. The pods of Hairy Senna are somewhat flattened, and straight to slightly down-curved. Those of the other species are all rounded or almost rounded in cross-section, apart from Candle Bush and Popcorn Senna which can be distinguished by their numerous (more than seven) pairs of leaflets (Navie 2004).

Why Is It A Weed?

What are its impacts?

Agriculture: Hairy Senna invades and can completely dominate pastures and other disturbed areas, and has the potential to become a major weed of crops within two or three seasons. Once established, Hairy Senna can remain a problem for many years as the seed remains viable for up to 10 years in the soil (Land Protection 2006).

How does it spread?

Hairy Senna is dispersed only by seed. Seed is sometimes eaten by stock and then germinates in the dung. Seeds may also be carried by water or spread as contaminants of agricultural produce or in mud sticking to animals, humans, machinery and vehicles (PIER 2003; Navie 2004; Land Protection 2006).

What is its history in Australia?

It is not known how Hairy Senna arrived in Australia. It was collected near Atherton, Queensland in 1960 (Queensland Herbarium 2008).

How To Manage It?

Best practice management

Prevention is the best method for controlling Hairy Senna, however it can be controlled by physical and chemical means. 

Non-chemical control: Manual control: Slashing can be undertaken to reduce old plants to a manageable size; however, this alone will not kill the plants. Slashing should be carried out while the plants are flowering and before seed set. Rotary hoeing or discing infested areas and immediately sowing with improved pasture can be effective, provided that the grasses are well managed and spot spraying of individual Hairy Senna plants is carried out. Maintaining the improved pasture helps to exclude sunlight and maintain soil moisture which hastens the decomposition of the seed reserves and limits seed germination. To help prevent spread stock should not graze in paddocks containing Hairy Senna. Machinery should be cleaned on site to stop possible spread.

Chemical control: Chemical control by spraying is most effective on young seedlings and it becomes more difficult, requiring more herbicide, with increasing plant age (Land Protection 2006, QLD DAF 2020).

Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?


When does it grow? (lifecycle/growth calendar)

Hairy Senna flowers all year round in South-East Asia (ICRAF undated).

Where Is It Found?

Which states and territories is it found?


What areas within states and territories is it found?

Hairy Senna is a perennial weed of pastures and rainforests in coastal Queensland and northern New South Wales. Dense infestations occur north of Mackay and southwest of Ingham as well as in some parts of the Atherton Tableland. It has also been recorded in the Northern Territory (Land Protection 2006).

Where does it originate?

Hairy Senna is a native of South America, most likely Brazil (PIER 2003).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?


Where is it a declared weed?


Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?


Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?


Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Senna hirsuta

Other scientific names (synonyms)?

Cassia hirsuta L.

Does it have other known common name(s)?

Sicklepod, Woolly Senna, Slimpod Glaberrima Senna, Woolly Wild Sensitive Plant, Shower Tree Senna, Stinking Cassia

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