Family: - Fabaceae.Names:
Summary:Hairless perennial shrub. 400-1500mm tall, spiny. Much branched. Constricted seed pods arising from spurs or spines. Small leaves.
Leaves:Alternate. Blue-green. Single at branch or spine nodes. May fall in hot weather. Exude a sugary exudate or "manna" called Persian manna.
Stems:Up to 1500 mm with many widely spreading branches. Awl shaped spurs or thorns 5-50mm 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.
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. 25mm long. Small beak at the tip.
Seeds:Yellow to red-brown or greyish-brown. Kidney shaped, 2-3 x 2mm. Smooth. Remain viable in the soil for many years but require special conditions to germinate.
Roots:Extensive root systems to 2000mm deep and 8000mm wide. Vertical roots with horizontal roots, about 1000mm 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.
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.
Distribution:NSW, SA, VIC, WA.
Habitats:Often on irrigation channels.
Climate:Semi-arid, temperate and sub-tropical.
Soil:Clayey and alkaline soils preferred.
Plant Associations:Irrigated pasture species.
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.
Plants of similar appearance:References:
Acknowledgments:Collated by HerbiGuide. Phone 08 98444064 or www.herbiguide.com.au for more information.