Family: Brassicaceae

Armoracia rusticana (Horseradish) is a hardy perennial plant native to Eastern Europe and Western Asia. It is best known for its large, spicy root, which is commonly grated and used as a pungent condiment in cooking. Horseradish grows as a leafy green plant with tall, coarse leaves and produces small clusters of white flowers in late spring to early summer. While it is prized in gardens for its culinary uses, it can spread aggressively if not carefully managed.

In Hawaii, horseradish is not considered invasive, but gardeners should be aware that it can take over garden spaces if left unchecked. It prefers moist, well-drained soils and plenty of sunlight, making it relatively easy to grow in home gardens. Gardeners who enjoy fresh horseradish roots can harvest them in the fall or winter, and the plant will return year after year if cared for properly.

High Risk Traits:

• Broad climate suitability (able to grow in >5 hardiness zones)
  
• Can grow in tropical climates at higher elevations
  
• Widely naturalized
  
• Weedy in gardens and cultivated settings
  
• Agricultural weed
  
• Potentially allelopathic
  
• Can poison livestock if consumed in large quantities
  
• May be an irritant to humans and potentially toxic if consumed in large quantities
  
• Tolerates many soil types
  
• Seeds dispersed intentionally by people (but rarely seeds)
  
• Able to spread vegetatively and from root fragments
  
• Can reproduce in one growing season
  
• Able to resprout after cutting and tilling

Low Risk Traits:

• Despite weediness, long history of cultivation and use by humans for food
  
• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock (palatable despite reports of toxicity)
  
• Possibly Shade-intolerant
  
• Rarely sets seed
  
• Lack of seed production limits dispersal capability
  
• Herbicides provide effective control