Family: Sapindaceae

Origin, Description & Uses
Ungnadia speciosa, commonly known as Mexican buckeye, is native to southern New Mexico, Texas, and northern to eastern Mexico. It is a large deciduous shrub or small tree, typically growing 10–30 feet (3–9 m) tall, with an open, rounded crown and attractive pink to rosy-purple flowers that bloom in early spring before or as the leaves emerge. The tree produces distinctive three-lobed seed capsules that split open in autumn to reveal glossy black seeds. Despite their resemblance to true buckeyes, the seeds belong to a different plant family and are toxic if consumed. Mexican buckeye is valued as an ornamental for its colorful spring flowers, attractive foliage that often turns yellow in fall, and tolerance of heat, drought, and limestone soils. It is well suited to xeriscapes, wildlife gardens, and naturalistic landscapes, where it also provides nectar for native pollinators.

Risks & Threats
Mexican buckeye is considered a low-risk species for Hawaii. It has not been reported as naturalized in the Hawaiian Islands or other tropical regions, and there is no evidence that it spreads aggressively beyond cultivation. The species reproduces primarily by seed, but dispersal is generally limited because the heavy seeds fall close to the parent plant and are not readily transported long distances. It lacks characteristics commonly associated with invasive plants, such as rapid growth, prolific seed production, or the ability to form dense, self-sustaining populations in natural habitats. While the seeds and other plant parts are poisonous if ingested and should be kept away from children and pets, this represents a human and animal safety consideration rather than an ecological threat. When planted responsibly, Ungnadia speciosa is considered a suitable ornamental tree with minimal risk to Hawaii’s native ecosystems.

High Risk Traits:

• Elevation range exceeds 1000 m, demonstrating environmental versatility
  
• Grows in subtropical climates
  
• Possibly naturalized (unable to confirm)
  
• Unpalatable to animals
  
• Toxic to animals
  
• Seeds toxic to people
  
• Reproduces by seeds
  
• Reaches maturity in 3 years
  
• Seeds dispersed by water, possibly carried by animals and intentionally planted by people
  
• Able to coppice and resprout after cutting

Low Risk Traits:

• No reports of invasiveness, but no evidence of widespread introduction outside native range
  
• Unarmed (no spines, thorns or burrs)
  
• Ornamental
  
• Shade-intolerant