Plant Pono

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Background of native Hawaii forest

Credit: Forest & Kim Starr

Canavalia cathartica (maunaloa, poisonous sea bean, purge vine, wild bean)

Family: Fabaceae

Canavalia cathartica, (maunaloa) is a legume native to the paleotropic kingdom, encompassing Asia, Africa, and Oceana. In Hawaiʻi, it is sometimes utilized in the creation of lei. In coastal India, the cooked seeds serve as a famine food, offering a high protein content compared to counterparts such as pigeon pea, chickpea, and cowpea. However, the seeds are toxic if not cooked. Additionally, it finds utility as green manure, cattle fodder, and food for rabbits and hares. In Micronesia, it serves as a medicinal remedy for coughs. The plant is also grown on beaches to prevent the erosion of sand. It is reported to be naturalized on the islands of Kauaʻi, Oʻahu, Molokai, Maui, and Hawaiʻi. It is an environmental weed in Hawaiʻi Volcanoes National Park, and its smothering growth habits and persistent seed bank can cause issues in Hawaiʻi’s ecosystem.


High Risk Traits:

  • Thrives, and spreads, in regions with tropical climates
  • Naturalized on Kauai, Oahu, Molokai, Maui, and Hawaii (Hawaiian Islands)
  • A weed in cultivated areas, waste places, inland plantations and disturbed forests.
  • A potential agricultural and environmental weed (controlled in Hawaii Volcanoes National Park)
  • Other Canavalia species have become invasive
  • Seeds are toxic unless cooked
  • Climbing and smothering growth habit
  • Reproduces by seeds
  • Hybridizes with other Canavalia species
  • Seeds dispersed by water and intentionally by people
  • Seeds impermeable to water for at least 1 1/2 years; can form a persistent seed bank

Low Risk Traits:

  • Despite reports of weediness, negative impacts are generally unspecified
  • Unarmed (no spines, thorns, or burrs)
  • Provides fodder for livestock (although mature seeds may be toxic)
  • Distribution appears to be limited to coastal habitats with high light levels and sandy, well-drained soils
  • May be self-incompatible, limiting seed set
  • Aside from water and intentional cultivation, large seeds unlikely to be accidentally dispersed
  • Seeds reported to lack buoyancy, potentially limiting dispersal distance by water