Family: Asteraceae

High Risk Traits:

• Broad climate suitability
  
• Naturalized, and able to spread in regions with tropical climates
  
• Naturalized on Kauai, Oahu, Maui, Lanai, and Hawaii (Hawaiian Islands), and widely naturalized elsewhere
  
• A weed of gardens, nursery stock, waste areas, and turfgrass, as well as several crops
  
• An environmental weed in some locations
  
• Other species are invasive
  
• Allelopathic
  
• Possibly toxic to animals and people if consumed in large amounts
  
• Pollen is allergenic
  
• Tolerates many soil types
  
• Able to form dense, monospecific stands
  
• Able to reproduce by seeds (in some locations) and vegetatively by rhizomes
  
• Reaches maturity in 2 years
  
• Seeds dispersed by wind, water, and people
  
• Rhizome fragments dispersed accidentally by machinery and as a contaminant of nursery stock
  
• Tolerant of, and difficult to control with many herbicides

Low Risk Traits:

• Valued as a garden herb by some, despite reports of weediness and possible toxicity
  
• Unarmed (no spines, thorns, or burrs)
  
• Propagated vegetatively in Hawaii, suggesting seed production may be low
  
• Limited seed production may limit ability for long distance dispersal