Family: Asteraceae

Origin, Description & Uses
Senecio vulgaris (common fireweed, common groundsel) is a small, fast-growing annual herb in the aster family (Asteraceae) native to Macaronesia, Europe, extending through temperate Asia to China and the Arabian Peninsula. It is now widely distributed across temperate regions worldwide and commonly occurs in disturbed soils such as gardens, agricultural fields, roadsides, and waste areas. The plant has deeply lobed green leaves and produces small yellow flower heads that can occur year-round under suitable conditions. While it has been used in limited traditional herbal practices, it is widely regarded as toxic due to pyrrolizidine alkaloids that can pose risks to livestock and humans if ingested.

Risks & Threats
In Hawaiʻi, Senecio vulgaris is naturalized on Maui (including Haleakalā) and on Hawaiʻi Island (including Parker Ranch and Ahumoa), and it is likely more widespread than currently documented. First recorded in the islands in 1938, it continues to persist in disturbed upland and agricultural habitats. This species possesses traits that are cause for concern, including rapid life cycle completion, prolific seed production, and strong adaptability to a wide range of environments, which can enable further spread in vulnerable ecosystems. As a naturalized species, it could detrimentally impact tropical island ecosystems by competing with native and beneficial plants in disturbed areas. Where already established, its spread should be managed or prevented in areas where it is not yet widely distributed to reduce further negative impacts.

High Risk Traits:

• Broad climatic and environmental versatility
  
• A temperate species naturalized in areas with tropical or subtropical climates
  
• Widely naturalized, including on Maui and Hawaii islands
  
• A weed of gardens, lawns, flower beds, waste places, arable land, roadsides and several crops
  
• Other Senecio species are invasive weeds
  
• May poison livestock
  
• Host of crop viruses
  
• Tolerates many soil types
  
• Reproduces by seed
  
• Hybridizes with other Senecio species
  
• Self-fertile
  
• Reaches maturity rapidly (<1 year)
  
• Seeds dispersed by wind, water, in contaminated crop seeds, and on farm vehicles and equipment
  
• Prolific seed production
  
• Seeds may persist in the soil, although longevity varies
  
• May be resistant to some herbicides

Low Risk Traits:

• Palatable to animals and edible to people
  
• Limited vegetative spread
  
• Herbicides may provide effective control