Family: Dioscoreaceae

Origin, Description & Uses
Dioscorea bulbifera, commonly known as air potato or hoi, is a vigorous twining vine native to parts of Africa and Asia. It produces distinctive aerial tubers (bulbils) along its stems that resemble small potatoes. Unlike the true yam Dioscorea alata (uhi), which develops a large underground tuber and is a recognized Polynesian canoe plant in Hawaiʻi, air potato primarily spreads through these above-ground bulbils. In some tropical regions, certain varieties of D. bulbifera have been used as a famine food after extensive processing to remove naturally occurring toxins. Although occasionally suggested as a possible Polynesian introduction, its status as a confirmed canoe plant in Hawaiʻi remains uncertain and is not consistently supported in standard historical or ethnobotanical references.

Risks & Threats
In Hawaiʻi, air potato is naturalized and possesses traits that are cause for concern. This fast-growing vine climbs aggressively over trees, shrubs, and fences, forming dense mats that block sunlight and smother surrounding vegetation. It reproduces readily from abundant aerial bulbils that detach, fall to the ground, and sprout, making management challenging once established. Because of its rapid growth and efficient vegetative spread, this species could detrimentally impact tropical island ecosystems, particularly in disturbed forests and unmanaged landscapes. Plant Pono recommends avoiding this species and instead choosing culturally appropriate and lower-risk alternatives such as Dioscorea alata (uhi), the traditional canoe yam cultivated in Hawaiʻi.

High Risk Traits:

• Environmental Weed: FLEPPC Category I; alters and displaces native communities.
  
• Weedy Congener: D. oppositifolia is highly invasive.
  
• Widely Naturalized: Established in Americas, SE USA, Hawaii, and Pacific islands.
  
• History of Introductions: Cultivated and spread by humans for millennia.
  
• Toxic: Contains alkaloids toxic to humans (if raw) and livestock (fatal to pigs).
  
• Smothering Growth: Twining vine overtops and kills vegetation.
  
• Vegetative Reproduction: Spreads rapidly via prolific aerial tubers (bulbils).
  
• Rapid Maturity: Bulbils germinate within weeks of dropping.
  
• Dispersal: Spreads via garden waste and intentional planting (food/medicine).
  
• Tolerates Wide Conditions: Shade-tolerant; grows in various soil types.
  
• Difficult to Control: Requires repeated, multi-year herbicide application.

Low Risk Traits:

• Sterile Seeds: Seeds generally non-viable in introduced ranges (e.g., Florida).
  
• No Seed Bank: Bulbils germinate quickly; no long-term persistence.
  
• Fire-Susceptible: Controlled burns effectively kill stems and bulbils.
  
• No Physical Defenses: Lacks spines, thorns, or burrs.