Family: Asteraceae
High Risk Traits:
- Broad climate suitability
- Possibly naturalizing on Oahu, Hawaiian Islands; widely naturalized elsewhere
- A weed impacting crop production and native vegetation in certain parts of the world
- Other Helianthus species are invasive
- Allelopathic
- Thrives in full sun, but tolerates shade
- Tolerates many soil types
- Forms dense stands that exclude other vegetation
- Reproduces by seeds and vegetatively by tubers and rhizomes
- Capable of reaching maturity in one season
- Seeds and tubers dispersed by soil movement, water, and intentionally by people
- Seeds exhibit dormancy and could potentially form a persistent seed bank
- Able to resprout from tubers and rhizomes after cutting or mowing
Low Risk Traits:
- A temperate species that may only thrive in higher elevations of tropical islands
- Unarmed (no spines, thorns, or burrs)
- Non-toxic
- Palatable to animals and people
- Mostly outcrossing and largely self-incompatible
- Limited seed production could reduce risk of long-distance dispersal
- Herbicides may provide effective control