Quick Facts

Quick facts

• Camel Thorn (Alhagi maurorum) is a native plant of western Europe and central Asia that has become an agricultural weed in other parts of the world including Australia.
• It is a spiny shrub with pink, purplish-yellow or red pea flowers.
• It can form large patches due to vegetative spread by rhizomes (underground stems).
• It competes with crop plants and preferred forage species and it is important that Camel Thorn is controlled before it establishes among valuable crop or stock plants or in native vegetation.
• Herbicide treatments are currently the most effective means of control for Camel Thorn.

What Does It Look Like?

What is it?

Camel Thorn (Alhagi mauroru) is a stiff perennial shrub that grows up to 1.5 m high that produces long rhizomes (underground stems). The main branches are erect, mostly hairless, finely ribbed and pale greyish-green in colour. The leaves are blue-green, 5-30 mm long, 2-14 mm wide, somewhat succulent and are usually borne at the base of spike-tipped side branches (spines) up to 6 cm long.

The flowers are purplish-red and yellow pea flowers, approximately 6-12 mm long with a short slender pedicel. The number of flowers varies from 1 to 6 arising from the axillary spines (CABI, 2020). Flowers occur from November to February.

The fruit are seed pods which are red-brown, 8-30 mm long, about 3 mm wide, deeply constricted between the seeds and usually has a small beak at the tip. The pod contains 1-5 seeds (occasionally up to 8). The kidney-shaped seeds are smooth, 2-3 mm long and 2 mm wide and a mottled greyish-brown, red-brown or yellow colour (Parsons & Cuthbertson 1992; Jeanes 1996; Thorp & Wilson 1998 – ; Western Australia Department of Agriculture and Food undated).

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

Flower colour

Yellow, Purple, Pink, or Red

Growth form (weed type/habit)

Shrub

Where it currently grows? Preferred habitat

In Australia, Camel Thorn occurs in pastures and neglected lands in arid to semi-arid areas, especially where there is a high moisture level in the subsoil. In Victoria and New South Wales, it is found mostly along drainage lines in irrigated pasture. Because Camel Thorn has roots that can extend 2-3 m into the ground, it can grow in dry, rocky, saline soil (Parsons & Cuthbertson 1992; Jeanes 1996; Gardner 2002; Western Australia Department of Agriculture and Food undated).

Are there similar species?

It is not known if Camel Thorn is commonly mistaken for other species in Australia.

Why Is It A Weed?

What are its impacts?

Agriculture: The vigorous root and rhizome system of Camel Thorn facilitates its spread and it has become a troublesome weed in other countries in cereal and horticultural crops where repeated cultivation aids its spread. In the United States it competes with, and eliminates, other vegetation including crop plants, preferred forage plants for stock and native species, and is itself grazed sparingly by stock.

Native ecosystems:  It is unknown if the plant affects biodiversity in Australia, but presumably it would have some negative impact due to its invasive nature and impacts on native vegetation have been recorded in the United States (Thorp & Wilson 1998 – ; CWMA undated; Western Australia Department of Agriculture and Food undated).

Urban areas: The rhizomes can extend under sealed roads and the shoots can break through bitumen.

Health: Positive impacts on human health are recorded: in the Middle East a sugary exudate from the leaves known as manna is used as a laxative, purgative, diuretic and expectorant while in India, oil from the leaves is said to relieve rheumatism (Parsons & Cuthbertson 1992).

How does it spread?

Camel Thorn reproduces mainly by rhizomes that can spread up to 10 m horizontally and produce aerial shoots up to 7.5 m away from the parent plant. New shoots produce woody roots that may extend 2-3 m into the ground. In this way, the radius of a patch can extend by up to 8 m a year. Broken rhizome pieces can give rise to new plants and can be spread to new areas by cultivation equipment or attempting physical removal. The seeds of Camel Thorn appear to need scarification (breaking or softening of the hard seed coat) before they will germinate, for example by passing through a ruminant (cattle, sheep, goats etc.).

Spread by seed appears to be insignificant, at least in Australia, where Camel Thorn is grazed sparingly by stock and seedlings are rarely found (Parsons & Cuthbertson 1992; Thorp & Wilson 1998 – ; CWMA undated; Western Australia Department of Agriculture and Food undated).

What is its history in Australia?

Camel Thorn was probably introduced to Australia in the early 1900s. The means of introduction is not known but in the United States it is suspected to have arrived as a contaminant in alfalfa seed. In Victoria, it was first collected at Rutherglen in the north-east of the state in 1915 and considered to be naturalised there by 1919. A second Victorian collection was made from the Tongala irrigation district in 1920. It was discovered in South Australia in 1922 and in Western Australia, where a patch of over 100 hectares was found at Kalgoorlie. By the early 1990s the Kalgoorlie patch had been reduced to about 10 hectares (Parsons & Cuthbertson 1992; National Herbarium of Victoria 2007; Thorp & Wilson 1998 -; CWMA undated).

How To Manage It?

Best practice management

Camel Thorn is a summer-growing species and is adapted only to very restricted habitats. It has proved unable to spread rapidly. It does not seed every year, is grazed by cattle in the growing season, and most infestations have been destroyed since picloram came into use (SA DEW, 2020).

Non-chemical control: Manual removal: of Camel Thorn, especially in established patches, is only effective if all fragments of rhizomes capable of developing into whole new plants are removed.

Chemical control: Herbicides that act through the soil will control Camel Thorn, but this method of treatment is problematic because it also affect other plants. Consequently, it is important that Camel Thorn is controlled before it establishes among valuable crop or stock plants or in native vegetation. Because of the extensive rhizome system, areas treated with herbicides need to be checked in subsequent years for regrowth. (Parsons & Cuthbertson 1992, CWMA undated).

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)

The above-ground parts of Camel Thorn die back in autumn and new shoots emerge from underground parts (rootstocks and rhizomes) in spring. Seeds also germinate in spring and rapid root growth ensures establishment before other species. Plants don't generally flower until they are one year old. Flowers are produced from November to February. 700-4000 seeds are produced per plant in dry conditions and lower numbers in moist shady conditions. Seeds may survive for a number of years (Parsons & Cuthbertson 1992; Thorp & Wilson 1998 -; CWMA undated).

Where Is It Found?

Which states and territories is it found?

NSW, SA, VIC, WA.

What areas within states and territories is it found?

Camel Thorn is sparsely distributed in south-eastern and south-western Australia. In New South Wales it is recorded from the plains of the far west and the south-west at Broken Hill and Wakool respectively, and further east on the central-western and south-western slopes. In Victoria it is known from three widely dispersed localities along the valley of the Murray River. In South Australia it has been recorded in the south-eastern corner of the state at seven localities including the Adelaide suburb of Wingfield as well as the Murray River fruit growing regions. In Western Australia it is known only from near Kalgoorlie (Parsons & Cuthbertson 1992; Gardner 2002; AVH 2007; National Herbarium of Victoria 2007; Spooner et al. 2007).

Where does it originate?

Camel Thorn is native to western Europe and central Asia (Jeanes 1996).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, VIC, 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

Alhagi maurorum

Other scientific names (synonyms)?

• Alhagi pseudalhagi Desv. ex B.Keller & Shap.
• Alhagi camelorum Fisch.
• Hedysarum alhagi L.
• Hedysarum pseudalhagi M.Bieb.

Does it have other known common name(s)?

Camel-thorn, Camelthorn Bush, Caspian Manna, Jawasa