Family: Asteraceae

High Risk Traits:

• Broad climate suitability (>5 hardiness zones and broad natural and introduced ranges)
  
• Naturalized in regions with tropical climates
  
• Naturalizing on Maui (prior to control by Maui Invasive Species Committee); widely naturalized elsewhere
  
• A disturbance-adapted agricultural and environmental weed
  
• Spiny
  
• May be high in nitrates and potentially toxic to grazing animals
  
• Tolerates many soil types
  
• Forms dense thickets that exclude other vegetation
  
• Reproduces by seeds
  
• Self-fertile
  
• Can reach maturity in 1-2 years
  
• Seeds dispersed by wind, water, in mud stuck to animals and machinery, as a contaminant and intentionally by people
  
• Prolific seed production
  
• Seeds remain viable for at least 9 years

Low Risk Traits:

• Palatable to browsing/grazing animals
  
• Requires full sun (shade limits ability to spread)
  
• Not reported to spread vegetatively
  
• Herbicides provide effective control