A purple/red, tufted annual grass to 600 mm diameter with upward bending stems, up to 800 mm tall, and a cylindrical spiny seed head that is often partially enclosed in the top sheath.
As A Soil Indicator:
Very low Calcium, High Potassium, High Phosphorus, Very high Magnesium, Very high Manganese, Very high Iron, High Sulfate, High Copper, High Zinc, High Boron, High Chloride, High Selenium, High Aluminum  Very little organic matter,  anaerobic activity, Sandy, well drained, low fertility soils.
Life cycle: 
Annual. Seeds germinate mainly in spring to summer and it grows rapidly, especially after heavy summer rains. Burrs produced from December to April. Most plants die in winter but a few may survive and set more seed in spring.
Fodder when young before the burrs develop.. 
Burrs puncture skin to degrade hides and cause ulcers in sheep mouths.
The seed formed first is the largest and will germinate in a few months. Others are dormant for up to 3 years. Up to 1000 seeds per plant produced.
Seed can germinate and establish from 250 mm deep. Burrs on the soil surface rarely germinate.
Secondary infections may develop from physical damage, especially around the mouth

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