Family: Apocynaceae
Origin, Description & Uses
Willughbeia coriacea, commonly known as Borneo rubber, is a tropical woody climber or liana native to southern Thailand, Peninsular Malaysia, Sumatra, Borneo, and surrounding parts of western Malesia. It belongs to the dogbane family (Apocynaceae) and produces thick, leathery leaves, fragrant flowers, and large, round fruits with a sweet, edible pulp that is enjoyed fresh in parts of its native range. The plant also produces a milky latex, which has been used locally as a source of natural rubber, although it has never become a major commercial crop. Because of its attractive foliage and unusual edible fruit, it is sometimes cultivated in tropical gardens and agroforestry systems.
Risks & Threats
Willughbeia coriacea is considered a low-risk species for Hawaiʻi. There is no evidence that it has become invasive or naturalized in the Hawaiian Islands or in other tropical regions where it has been cultivated. While its fleshy fruits may be eaten by wildlife, there is no indication that the species spreads aggressively or forms dense infestations. As with any introduced plant, it should be grown responsibly and monitored for unexpected spread, but current evidence suggests it poses little threat to Hawaiʻi’s native ecosystems and can be considered an appropriate choice for cultivation.
High Risk Traits:
- Thrives in tropical climates
- Climbing, and potentially smothering, growth habit
- Reproduces by seed
- Seeds dispersed by mammals and intentionally by people
- Seeds dispersed by birds and intentionally by people
- Limited ecological information reduces 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)
- Edible fruit
- Medicinal uses
- Fruit relatively large and unlikely to be accidentally dispersed
