Family: Apocynaceae

Origin, Description & Uses
Pachypodium horombense (horombe clubfoot, yellow bell pachypodium) is a succulent plant native to south-central Madagascar, where it grows in rocky, seasonally dry habitats. It is a striking member of the Pachypodium group, known for its thick, swollen trunk (caudex) that stores water and helps it survive drought. The plant produces long, narrow leaves and showy, pale yellow to yellow-green, bell-shaped flowers that appear near the top of its stem. Because of its unusual form and ornamental flowers, it is sometimes grown by succulent enthusiasts and in specialty botanical collections in dry or Mediterranean-style gardens.

Risks & Threats
This species is considered low risk for invasiveness and is not known to be naturalized or weedy outside of cultivation. It has specialized growth requirements, including well-drained soils and warm, dry conditions, which limit its ability to spread aggressively in most environments. There are no significant reports of it posing threats to natural ecosystems or agricultural systems. As with many ornamental succulents, the main concerns are related to over-collection in its native range and ensuring that cultivated plants are sourced responsibly rather than from wild populations.

High Risk Traits:

• Grows in tropical climates
  
• Spiny
  
• Genus reportedly toxic
  
• Reproduces by seeds
  
• Reaches maturity in 2 years
  
• Seeds likely dispersed by wind and people
  
• Able to regenerate after cutting or damage

Low Risk Traits:

• No reports of invasiveness or naturalization, but limited evidence of widespread introduction outside native range
  
• Landscaping and ornamental value
  
• Specialized pollinator requirements (likely limits seed set outside native range)
  
• Not reported to spread vegetatively