Family: Scrophulariaceae

Buddleja paniculata, commonly called butterfly bush, is a flowering shrub native to the Himalayas and parts of Southeast Asia. It grows as a medium-sized, many-branched shrub with soft, gray-green leaves and long, fragrant clusters of white to pale lilac flowers. These blooms are highly attractive to butterflies and other pollinators, which has made the plant popular for ornamental use in its native range and other regions where it has been introduced.

In Hawaiʻi, Buddleja paniculatais rated high risk due to traits that could allow it to escape cultivation and potentially cause problems in natural areas. Like other Buddleja species known to become invasive elsewhere, it can produce large numbers of wind-dispersed seeds, grow quickly, and establish in disturbed sites. Although it is not widely planted in the islands, these biological characteristics mean it could spread if introduced more broadly. Because of this risk, it is best to avoid planting B. paniculata and instead choose safe, non-invasive alternatives that support pollinators without threatening Hawaiʻi’s native ecosystems.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Grows in tropical and temperate climates
  
• Other species have become invasive
  
• Tolerates many soil types
  
• Reproduces by seeds
  
• Hybridizes with other Buddleja species
  
• Seeds dispersed by wind, secondarily by water and intentionally by people
  
• Able to coppice and resprout after cutting
  
• Limited ecological information may reduce accuracy of risk prediction

Low Risk Traits:

• No reports of invasiveness or naturalization, but no evidence of widespread introduction outside native range
  
• Unarmed (no spines, thorns, or burrs)
  
• Ornamental
  
• Dioecious (requires male and female plants to produce viable seed
  
• Herbicides may provide effective control