Family: Geraniaceae

Geranium maderense (giant herb-Robert, Madeira cranesbill) is a rare herbaceous perennial native to Madeira. Geranium maderense is widely cultivated in Madeira, in gardens, and is naturalized near cities. It is listed as critically endangered under the IUCN. It is reported to be naturalized in the UK and New Zealand but no evidence in the Hawaiian Islands to date. This plant is reported to be a nuisance in New Zealand. Also, other Geranium species are invasive weeds. It is shade tolerant, tolerates many soil types, reproduces by seeds, may hybridize with other Geranium species, and is self-fertile, all of which are high-risk qualities.

High Risk Traits:

• Grows in subtropical to Mediterranean climates
  
• Naturalized in the UK and New Zealand (but no evidence in the Hawaiian Islands to date)
  
• Seedling recruitment reported to be a nuisance in New Zealand
  
• Other Geranium species are invasive weeds
  
• Unpalatable to deer, rabbits, and possibly other animals
  
• Shade tolerant
  
• Tolerates many soil types
  
• Reproduces by seeds
  
• May hybridize with other Geranium species
  
• Self-fertile
  
• Reaches maturity in two to three years
  
• Seeds dispersed through explosive dehiscence, and through intentional cultivation

Low Risk Traits:

• No significant negative impacts reported where naturalized
  
• Unarmed (no spines, thorns, or burrs)
  
• Non-toxic
  
• Not reported to spread vegetatively