Family: Asteraceae

Arnica montana, commonly known as European arnica or leopardsbane, is a perennial herb native to the mountainous regions of Europe. It is famous for its bright yellow, daisy-like flowers and its historical use in traditional herbal medicine, particularly for treating bruises, sprains, and muscle aches. While all parts of the plant may be toxic if ingested, it is prized in gardens for its striking blooms and medicinal associations when used externally.

In Hawaii, European arnica is not naturalized, although it has established itself in other regions outside its native range. Despite having certain traits that could allow it to spread, it is currently considered a safe planting choice in the Hawaiian Islands. It grows best in cool, well-drained, sunny areas, and gardeners can enjoy its beauty without concern for ecological impacts—just remember to handle it with care.

High Risk Traits:

• Elevation range exceeds 1000 m in temperate climates
  
• Reported to be naturalized in North America
  
• Possibly toxic if ingested and handling may cause dermatitis
  
• Seeds dispersed by wind and intentionally by people
  
• Able to spread vegetatively by rhizomes
  
• Able to reach maturity in 1-2 years

Low Risk Traits:

• No reports of invasiveness or detrimental impacts found
  
• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock (palatable despite reports of toxicity)
  
• Medicinal uses
  
• Self-incompatible
  
• Seeds lack dormancy, and does not form a persistent seed bank