Ginger has been grown in tropical Asia since ancient times, and wild forms have not been found. It is now cultivated worldwide as an important spice plant in tropical climates with annual rainfall of. 2500-3000 mm. It rarely, if ever, produces seeds in cultivation, and is propagated vegetatively by pieces of rhizome called seed pieces or sets. It’s long history of cultivation with no reports of negative impacts, and its lack of seed production, contribute to its low risk of invasiveness in the Hawaiian Islands or other tropical island ecosystems.
High Risk Traits:
- Thrives and spreads in regions with tropical climates
- Reported to be naturalized where introduced (but no evidence in the Hawaiian Islands to date)
- Reported to be a weed in a few locations, but no evidence of negative impacts has been found.
- Other Zingiber species are invasive weeds.
- Possibly allelopathic.
- Unpalatable to deer, and probably other browsing animals.
- Shade tolerant, but also grows in full sun (could potentially establish in intact forest understory).
- May reproduce by seed, but this rarely occurs in cultivation.
- Propagated and reproduces vegetatively from rhizomes and fragments.
- Rhizomes spread intentionally through cultivation, and potentially by water or discarded garden waste.
- Seeds, if produced, are arillate, and might be dispersed by birds or ants (although this vector is unlikely to play an important role in spread).
- Capable of resprouting from rhizomes if foliage is removed or damaged.
Low Risk Traits:
- A widely cultivated food plant with no confirmed reports of invasiveness or negative impacts.
- Unarmed (no spines, thorns, or burrs)
- Plants in cultivation are non-toxic, although contact with or excessive consumption of rhizomes may cause sickness or an allergic reaction.
- Lack of seed production reduces the risk of long distance or accidental dispersal.
- Herbicides may provide effective control if needed.
- Bacterial wilt, and nematodes, would likely prevent or limit the spread of cultivated ginger into unmanaged or natural areas.