Family: Araceae

Origin, Description & Uses
Zantedeschia aethiopica, commonly known as calla lily or arum lily, is native to southern Africa. It is a clump-forming perennial with large, glossy, arrow-shaped leaves and distinctive white, funnel-shaped flower structures (spathes) surrounding a central flower spike. It is widely cultivated as an ornamental plant for its attractive foliage and flowers, and is commonly used in gardens, landscaping, and floral arrangements. Its tolerance of wet soils and ability to grow in shaded areas have contributed to its popularity in tropical and subtropical landscapes.

Risks & Threats
Zantedeschia aethiopica is naturalized in Hawaiʻi, including on Kauaʻi and Maui, and possesses traits that are cause for concern. It can spread through seeds and vegetative growth from rhizomes, allowing it to form dense patches that may displace native vegetation and alter tropical island ecosystems. This species could detrimentally impact native habitats by competing with native plants, particularly in moist and shaded environments. Where it is already widespread, management and preventing further use in areas where it is not yet established can help minimize additional negative impacts. When suitable alternatives are available, choosing low-risk or native plants instead of Zantedeschia aethiopica is recommended.

High Risk Traits:

• Broad climate tolerance (tropical to frost-prone, wet to dry)
  
• Naturalized in Hawaii, New Zealand, Australia, and the Americas
  
• Naturalized on Kauaʻi and Maui
  
• Garden, agricultural, and environmental weed
  
• Forms dense stands that displace native vegetation
  
• Toxic to livestock (cattle deaths reported)
  
• Toxic to humans (poisonous if ingested; skin irritant)
  
• Shade tolerant
  
• Wide soil tolerance, including waterlogging
  
• Reproduces via rhizome fragments
  
• Produces viable seeds (up to 500 per flower head)
  
• Seed dispersed by water, birds, and mammals
  
• Widely planted as ornamental (intentional dispersal)
  
• Difficult to eradicate; regrows from rhizomes after cutting
  
• Requires herbicides for effective control

Low Risk Traits:

• No spines, thorns, or burrs
  
• No persistent seed bank (seeds short-lived)
  
• Not wind-dispersed
  
• No external animal dispersal (no hooks/barbs)