Family: Asteraceae

Origin, Description & Uses
Calendula officinalis, commonly known as garden marigold or pot marigold, is native to the western Mediterranean region. It is an annual or short-lived perennial herb that grows to about 2 feet tall, with branching stems and bright yellow to orange, daisy-like flowers. It is widely cultivated as an ornamental and has also been used in traditional herbal preparations, cosmetics, and as a coloring agent.

Risks & Threats
Although Calendula officinalis is not known to be naturalized in Hawaiʻi, it possesses traits that are cause for concern. While generally considered non-invasive, it can spread readily under favorable conditions and occasionally escape cultivation, establishing in disturbed soils or along garden edges. It is not known to cause significant ecological impacts elsewhere, but caution is recommended in Hawaiʻi. Gardeners should monitor for volunteer plants and manage them if necessary to prevent the species from becoming locally persistent.

High Risk Traits:

• Widely naturalized elsewhere in the world (no evidence in the Hawaiian Islands to date)
  
• Broad climate suitability
  
• Unpalatable to deer and possibly other grazing animals
  
• May cause allergic reactions to susceptible individuals
  
• Tolerates many soil conditions (and potentially able to exploit many different habitat types)
  
• Self-compatible
  
• Reaches maturity in under 1 year
  
• Spread intentionally by people and possibly short distances by wind and gravity
  
• Often spread by discarded garden waste
  
• Seeds may persist in the soil

Low Risk Traits:

• Unarmed (no spines, thorns or burrs)
  
• Consumed by people
  
• Does not spread vegetatively
  
• Seeds not dispersed very far by natural means
  
• May be effectively controlled with herbicides
  
• Ornamental value