Family: Plantaginaceae

Origin, Description & Uses:
Linaria dalmatica (Dalmatian toadflax) is a perennial herb native to southeastern Europe, where it grows in dry, open habitats such as rocky slopes, roadsides, and disturbed areas. It is easily recognized by its bright yellow, snapdragon-like flowers with an orange throat and its smooth, bluish-green leaves that clasp the stem. The plant spreads both by seeds and creeping underground rhizomes, allowing it to form dense colonies. Dalmatian toadflax has been introduced to other regions as an ornamental plant due to its showy flowers and tolerance of poor soils and drought conditions.

Risks & Threats:
Dalmatian toadflax is considered a highly invasive weed in many parts of the world because of its aggressive growth and ability to outcompete native vegetation. It spreads rapidly through both seeds and vegetative rhizomes, forming dense stands that can reduce biodiversity, alter habitat structure, and degrade rangelands and natural ecosystems. It is also difficult to control once established due to its extensive root system. Although this species is currently not known to be naturalized in the Hawaiian Islands, it does possess traits that are cause for concern, and which could detrimentally impact tropical island ecosystems if it were to become established. Choosing a low-risk or native alternative is strongly recommended to help protect Hawaii’s unique environments.

High Risk Traits:

• Naturalized and weedy in Europe, Russia, Canada, and the US
  
• Agricultural and environmental weed; reduces crop yields and alters native communities
  
• Congeneric weed (Linaria vulgaris) is invasive
  
• Unpalatable and mildly toxic to livestock
  
• Tolerates wide range of coarse soils and moderate shade
  
• Reproduces vegetatively from root fragments
  
• Produces up to 500,000 seeds annually
  
• Persistent seed bank (up to 10 years)
  
• Wind-, water-, and intentionally dispersed by humans
  
• Seeds survive passage through cattle gut
  
• Tolerates fire and cultivation; control difficult

Low Risk Traits:

• Native to temperate climates; no tropical/subtropical naturalization
  
• No spines, thorns, burrs, or parasitic habit
  
• Self-incompatible (requires cross-pollination)
  
• No evidence of toxicity to humans or allergenicity
  
• No known pests/pathogens hosted