Family: Blechnaceae

Blechnum appendiculatum (palm fern, hammock fern) is a fern native to South America, United States, and the Caribbean. It is infrequently grown as a garden plant, and for living plant walls. It is reported to be naturalized on the islands of Kauaʻi, Oʻahu, Maui, Lanaʻi, Molokai and Hawaiʻi Island. This plant is an environmental weed that threatens rare and endangered plants in Hawaiian wet and mesic forests. It dominates the understory, outcompeting the native forest plants that are there. It spreads easily with its numerous spores, and by rhizomes, which can be spread by wind and water. 

High Risk Traits:

• Thrives in tropical climates
  
• Broad elevation range (exceeds 1000 m)
  
• Naturalized in the Hawaiian Islands
  
• Environmental weed (threatens rare and endangered native Hawaiian species)
  
• Shade tolerant
  
• Tolerates many soil conditions (and potentially able to exploit many different habitat types)
  
• Forms solid stands in understory
  
• Reproduces by prolific spore production
  
• Hybridizes with other Blechnum species
  
• Spreads vegetatively by rhizomes
  
• Spores dispersed by wind, and water

Low Risk Traits:

• Unarmed (no spines, thorns, or burrs)
  
• Non-toxic
  
• Herbicides may provide effective control