Camel Thorn

Alhagi maurorum Medik.

Synonyms - Alhagi camelorum, Alhagi persarum, Alhagi pseudalhagi.

Family: Fabaceae.

Names:

Camel Thorn - refers to the grazing of it by Camels in Asia. Alhagi is from haj, the Arabic name of the plant.
Camel Thorn Bush (S. Africa)
Caspian Manna
Hebrew manna
Jawasa (Hindi)
Moor's Alhagi.

Summary:

Hairless perennial shrub. 400-1500 mm tall, spiny. Much branched. Constricted seed pods arising from spurs or spines. Small leaves.

Description:

Cotyledons:

Two.

Leaves:

Alternate. Blue-green. Single at branch or spine nodes. May fall in hot weather. Exude a sugary exudate or "manna" called Persian manna.
Stipules - Small. Smooth edges. Small hairs when young, becoming hairless with age.
Petiole - Short.
Blade - Oval to wedge shaped. 5-30 mm long x 3-12 mm wide. Small near top, increase to 30 mm long near base. Edges entire.

Stems:

Up to 1500 mm with many widely spreading branches. Awl shaped spurs or thorns 5-50 mm long that end in a sharp spine that is often yellow. Rigid. Young branches may be hairy, older ones hairless. One to several stems from each crown.

Flowers:

Inconspicuous. Pea type in clusters of 1-8 on short branches or spurs near the ends of main branches. On short stalks on the spurs.
Bracts - 2 small bracts below the calyx. 7-10 mm long.
Ovary - Hairless.
Style - Incurved, hairless.
Calyx - 3-4 mm long with 5 shallow blunt teeth.
Petals - Brown to purple. Standard petal almost circular in outline and 10 mm diameter. Wings and incurved keel petals are 10 mm long
Stamens - 9 plus 1
Anthers -

Fruit:

Slender red-brown hairless pod with 1-9 seeds. Constricted between the seeds into globular segments but these generally do not break into separate segments. 25 mm long. Small beak at the tip.

Seeds:

Yellow to red-brown or greyish-brown. Kidney shaped, 2-3 x 2 mm. Smooth. Remain viable in the soil for many years but require special conditions to germinate.

Roots:

Extensive root systems to 2000 mm deep x 8000 mm wide. Vertical roots with horizontal roots, about 1000 mm deep. Underground stems (rhizomes). Regenerates from root fragments. The roots are very tough and vigorous and roadside infestations may break through the bitumen or travel under compacted roads.

Key Characters:

Biology:

Life cycle:

Perennial. Seeds germinate in autumn and spring and grow quickly forming an extensive root system. Most plant won't flower in their first year. Flowering occurs in spring and may extend into summer if moisture is available. Top growth dies in autumn and new shoots emerge from roots in spring. The main method of spread is by extension of the root system by up to 8 metres a year. Seedlings are rarely found. Root fragments carried by cultivating equipment also aid spread.

Physiology:

Reproduction:

Seeds, rhizomes, root fragments.

Flowering times:

November - December.

Seed Biology and Germination:

Seeds germinate in autumn or spring. Seeds may have to pass through the rumen of an animal before they will germinate.

Vegetative Propagules:

Rhizomes and root fragments.

Hybrids:

Allelopathy:

Population Dynamics and Dispersal:

Origin and History:

Southern USSR, Central Asia, India.

Distribution:

NSW, SA, VIC, WA.

Courtesy Australia's Virtual Herbarium.

Habitats:

Often on irrigation channels.

Climate:

Semi-arid, temperate and sub-tropical.

Soil:

Clayey and alkaline soils preferred.

Plant Associations:

Irrigated pasture species.

Significance:

Beneficial:

Fodder.
Cattle eat it more readily than sheep probably because of its spiny nature.

Detrimental:

Weed of pastures and neglected areas. Used as low value fodder. New growth or frost damaged plants grazed by cattle but not sheep. Weed of cereals and vegetables overseas.

Toxicity:

Not recorded as toxic.

Legislation:

Noxious weed of Vic, SA and WA.

Management and Control:

Cultivation is generally ineffective because root fragments regrow and much of the root system is too deep. The soil residual herbicide, picloram, has provided good control. Glyphosate, fosamine and clopyralid are also used. Hormone herbicides require multiple applications over a number of years. Flooding with water for several weeks has been used for control in California.

Thresholds:

Eradication strategies:

Herbicide resistance:

Biological Control:

Related plants:

None.

Plants of similar appearance:

References:

Black, J.M. (1965). Flora of South Australia. (Government Printer, Adelaide, South Australia). P481. Diagram of pod.

Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. and Leigh, J.H. (1992). Plants of Western New South Wales. (Inkata Press, Melbourne). P384. Photo.

Lamp, C. and Collet, F. (1990). A Field Guide to Weeds in Australia. (Inkata Press, Melbourne).

Lazarides, M. and Hince, B. (1993). CSIRO handbook of economic plants of Australia. (CSIRO, Melbourne). #49.1.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious weeds of Australia. (Inkata Press, Melbourne). P464-466. Photos.

Acknowledgments:

Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.