A recent introduction to Australia as a contaminant in pea of pasture seed. First recorded at Oberon in 1950. It is now an important weeds of improved pastures, roadsides and neglected areas. Dispersal is by seed with most seed falling within 1 to 2 meters of the plant. Spread is in mud, water, fodder and agricultural seed, or by machinery. Grows in dense patches and its spiny foliage discourages grazing. Successful control is achieved by establishing a perennial pasture to compete with seedlings in late Summer. Herbicide application is effective but timing of application is important.