Quick Facts

Quick facts

• Hairy Croton (Croton hirtus) is an upright annual herb that produces an offensive odour when crushed.
• It is covered with stiff, star-shaped hairs which may cause skin irritation.
• It grows in disturbed habitats including roadsides, gardens, pastures and cultivated areas from sea level to 700 m altitude and prefers sunny to lightly shaded positions.
• It is currently only recorded from one locality in Queensland.
• It appears to have the potential to be an environmental weed.

What Does It Look Like?

What is it?

Hairy Croton (Croton hirtus) is an upright annual herb growing up to 1 m high which produces an offensive-smelling odour when crushed. The whole plant is covered with stiff, star-shaped hairs which may cause skin irritation. The leaves are roughly egg-shaped in outline, 2.5–7.5 cm long by 1–5 cm wide and are arranged alternately or clustered into whorls (circular arrangement) of three along the branchlets. The leaf margin is finely toothed.

Hairy Croton produces separate male and female flowers which are borne on the same plant. The flowers are arranged in spike-like clusters (racemes) up to 4 cm long at the end of the branchlets. The green female flowers are borne at the base of the raceme while the white male flowers are borne towards the tip. Amongst the flowers on the raceme are gland-tipped, finger-like projections up to 5 mm long.

The fruiting capsules have three lobes, are about 4 mm across and green. The walls of the mature capsules split to release usually three seeds. The grey-brown seeds are about 3 mm long and finely ribbed, with a tiny white aril (fleshy outgrowth) at the tip (Henty & Pitchard 1973; Waterhouse & Mitchell 1998; Welzen & Chayamarit 2007).

For further information and assistance with identification of Hairy Croton, contact the herbarium in your state or territory.

Flower colour

White, Green

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Hairy Croton reportedly prefers sunny to lightly shaded positions. It commonly grows in disturbed habitats including roadsides, gardens, pastures and cultivated areas from sea level to 700 m altitude (Henty & Pitchard 1973; Waterhouse & Mitchell 1998).

Are there similar species?

No information on similar species in Australia has been found.

Why Is It A Weed?

What are its impacts?

Agriculture: Hairy Croton is recorded as a weed of agricultural and disturbed habitats such as roadsides. In south-east Asia it invades orchards, Tea plantations, Upland Rice, Tobacco, Peanuts and vegetable crops (Waterhouse & Mitchell 1988).

Native ecosystems: It also appears to have potential to be an environmental weed (Queensland Herbarium 2008).

How does it spread?

Hairy Croton is primarily spread through seed dispersal. The main animal vector for dispersal is ants (Waterhouse & Mitchell 1998). There is also evidence that it is spread by machinery as well as spread along watercourses by water movement (Queensland Herbarium 2008).

What is its history in Australia?

Hairy Croton is most likely an accidentally introduction. It was first recorded in Australia, near Weipa, Queensland at the Scherger RAAF Base in April 2003, but the species is believed to have been present in that location for sometime, perhaps since the construction phase of the Base in the early to mid 1990s (Queensland Herbarium 2008).

How To Manage It?

Best practice management

Chemical control: The Australian population of Hairy Croton have been controlled with herbicides and/or fire. Follow-up treatments are required as numerous seedlings emerge from beneath poisoned plants (Queensland Herbarium 2008).

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

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Hairy Croton is an annual plant that reproduces via seeds. It has been recorded flowering and fruiting in Australia from March and April (Queensland Herbarium 2008).

Where Is It Found?

Which states and territories is it found?

QLD

What areas within states and territories is it found?

Hairy Croton has only been recorded from one site near Weipa, Queensland (Queensland Herbarium 2008).

Where does it originate?

Hairy Croton is native to the tropical areas of North and South America (Waterhouse & Mitchell 1998).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, WA

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Croton hirtus

Other scientific names (synonyms)?

• Brachystachys hirta (L'Her.) Klotzsch
• Croton glandulosus subsp. hirtus (L'Her.) Croizat
• Croton glandulosus var. hirtus (L'Hér.) Mull.Arg.