Family: Malpighiaceae

Origin, Description & Uses
Callaeum macropterum, commonly known as yellow butterfly vine, is a fast-growing woody vine native to the southwestern United States and Mexico. It is valued as an ornamental for its bright yellow flowers, vigorous climbing habit, and distinctive butterfly-shaped seed pods that persist after flowering. This drought-tolerant vine is often planted on fences, trellises, and arbors in warm climates, where it provides colorful floral displays and attracts pollinators such as bees and butterflies. Its tolerance of heat and dry conditions has made it a popular landscape plant in subtropical and arid regions.

Risks & Threats
Although yellow butterfly vine is not known to be naturalized in Hawaii, it does possess traits that are cause for concern. Its rapid growth, climbing habit, and ability to produce abundant wind-dispersed seeds could allow it to spread beyond cultivation in suitable environments. Vigorous vines can potentially smother surrounding vegetation and compete with native plants for sunlight and space. Because tropical and subtropical island ecosystems can be especially vulnerable to aggressive ornamental vines, caution is recommended to ensure that this species will not negatively impact Hawaii. Ongoing evaluation and responsible planting practices are encouraged.

High Risk Traits:

• Congeneric weeds exist (M. pubiflora, M. coccinia)
  
• Toxic to animals (cattle, causes sudden death)
  
• Creates fire hazard (dead wood accumulation)
  
• Climbing, smothering growth habit
  
• Tolerates wide range of soil conditions
  
• Produces viable seed
  
• Minimum generative time = 1 year
  
• Propagules dispersed unintentionally (dried arrangements) and intentionally (ornamental)
  
• Wind-dispersed seeds (winged schizocarp)
  
• Persistent seed bank (>1 year)
  
• Tolerates pruning and mutilation

Low Risk Traits:

• No naturalization reported
  
• Narrow climate suitability (USDA Zones 8–11)
  
• No spines, thorns, or burrs
  
• No allelopathy, parasitism, or pest/disease host
  
• Not toxic to humans
  
• Not shade tolerant (requires full sun)
  
• Requires cross-pollination (not self-compatible)
  
• No vegetative fragmentation
  
• Not a produce contaminant
  
• Not dispersed by water, birds, animals, or gut passage
  
• Not prolific seed production