Family: Asteraceae

Tanacetum cinerariifolium, commonly known as pyrethrum, is a perennial flowering plant native to Albania and the northwestern Balkan Peninsula. It is a daisy-like plant with white ray flowers and yellow centers and is best known as the natural source of pyrethrins—compounds widely used in insecticides. Pyrethrum has a long history of cultivation and is grown commercially around the world for use in agricultural pest management, public health applications, and household insect control products. It typically thrives in sunny locations with well-drained soils.

At this time, pyrethrum is not known to be naturalized in Hawaiʻi, but it does possess traits that are cause for concern. Its perennial growth habit, ability to produce viable seed, and tolerance of disturbed environments suggest it could spread beyond cultivation under suitable conditions. In addition, its biologically active compounds may have unintended effects on local ecological interactions if the species were to establish in the wild. Given Hawaiʻi’s high vulnerability to invasive species, further evaluation is needed to determine whether pyrethrum could negatively impact native species or ecosystems, and the use of low-risk or native alternatives is encouraged where feasible.

High Risk Traits:

• Produces abundant viable seed, which can facilitate spread beyond cultivation
  
• Perennial growth habit, allowing plants to persist once established
  
• Adapted to a wide range of environmental conditions, particularly open, sunny sites
  
• Cultivated globally, increasing propagule pressure through repeated introductions
  
• Known to escape cultivation in some regions, particularly in disturbed habitats
  
• Allelopathic or chemically active compounds (pyrethrins) that may affect insects and alter ecological interactions
  
• Tolerance of disturbance, allowing establishment along roadsides, fields, and managed landscapes

Low Risk Traits:

• Not known to aggressively invade intact natural ecosystems
  
• Generally associated with agricultural or managed settings, rather than native forests
  
• Limited dispersal mechanisms, with seeds not adapted for long-distance natural spread
  
• Requires specific growing conditions (well-drained soils, full sun) that limit establishment in many habitats
  
• No evidence of forming dense monocultures that displace native plant communities
  
• Long history of cultivation without widespread severe ecological impacts
  
• Easily managed through conventional horticultural or agricultural practices