Family: Fabaceae
Lablab purpureus (hyacinth bean) is an annual or short-lived perennial, scandent (twining) or trailing herb believed to be native to the Old World tropics. It is one of the most diverse domesticated legume species and has multiple uses. Hyacinth bean is widely cultivated in the tropics and subtropics particularly in India and southeast Asia, Egypt and Sudan and is probably an ancient introduction to the Pacific islands. In the Hawaiian Islands it is cultivated and naturalized in dry to mesic, disturbed areas such as along roadsides and trails and abandoned homesites, from sea level to over 1000 m elevation, on all the main islands. It has a long history of cultivation in Hawaii and is not reported to have any serious negative impacts where grown or naturalized.
High Risk Traits:
- Broad elevation range
- Thrives and spreads in regions with tropical climates
- Widely naturalized, including the main Hawaiian Islands
- Sometimes reported as a weed of certain crops, but impacts to yield are not documented
- Extracts demonstrate allelopathic effects
- Seeds have a high content of toxic cyanogenic glucosides and trypsine (these toxic compounds are broken down by heat)
- Tolerates many soil types (spread not limited by substrate)
- Climbing and potentially smothering growth habit
- Reproduces by seed
- Self-fertile (both self- and bee-pollinated)
- Reaches maturity in one growing season
- Seeds dispersed by gravity, possibly accidentally along roads, trails, or as a soil contaminant, and through intentional cultivation
- Tolerant of repeated cutting and grazing
Low Risk Traits:
- No reports of serious negative impacts where cultivated or naturalized
- Unarmed (no spines, thorns, or burrs)
- Provides fodder for livestock and seed for human consumption (cooked)
- Intolerant of moderate to heavy shading (may inhibit spread)
- Not reported to spread vegetatively
- Relatively large seeds lack adaptations for long-distance dispersal
- Herbicides may provide effective control if needed