Family: Asteraceae

Arctium lappa (great burdock, greater burdock, gobo) is a large biennial herb native to Europe and Asia that has become naturalized on O‘ahu, Lāna‘i, and Hawai‘i Island. It produces large, heart-shaped leaves and tall flowering stalks bearing purple thistle-like flower heads that mature into spiny burrs. These burrs cling to clothing, animal fur, and feathers, aiding in the plant’s dispersal over long distances. Great burdock thrives in disturbed areas such as pastures, roadsides, and forest edges, where it can form dense stands that crowd out native vegetation and alter local plant communities.

In Hawai‘i, A. lappa is considered a high-risk species and is not recommended for cultivation. Its aggressive growth, effective seed dispersal, and ability to thrive in a range of environments contribute to its invasiveness. While it is sometimes cultivated elsewhere for its edible root, known as gobo, in Hawai‘i its spread poses ecological concerns. Preventing further planting and controlling existing populations where possible are important for protecting native and agricultural ecosystems.

High Risk Traits:

• Broad climate suitability, and elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Naturalized in regions with tropical climates
  
• Naturalized on Oahu, Lanai, and Hawaii (Hawaiian Islands) as well as North America and Australia
  
• A weed of disturbed areas and certain crops
  
• Other Arctium species are invasive
  
• Pointed, barbed bracts may harm eyes of animals, or tongues of dogs grooming themselves with the burrs stuck in their fur
  
• Host of crop pathogens
  
• Shade tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds, and may be able to regenerate from large, tuberous root
  
• Hybridizes with other Arctium species
  
• Reaches maturity in two years (biennial)
  
• Hooked outer phyllaries (bracts) facilitate animal (including human) dispersal of the heads. Heads may also be transported by water
  
• Seeds also dispersed as a produce contaminant
  
• Seeds may form a persistent seed bank (21+ years)
  
• May be able to resprout from roots if not completely removed

Low Risk Traits:

• A domesticated plant, long cultivated as a food crop. Harvesting prior to flowering minimizes risk of invasiveness
  
• Palatable to deer, and possibly other browsing animals, but burrs may deter browsing
  
• Herbicides may provide effective control