Kauaʻi record · kba_plant_ageratina_riparia
Hāmākua pāmakani
Ageratina riparia
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About Hāmākua pāmakani
Hāmākua pāmakani (Ageratina riparia) is recorded as an established shrub on Kauaʻi. A low, spreading subshrub with a creeping underground stem system and sprawling shoots roughly half a metre to one metre long. Narrow to elliptic leaves have sharp teeth. Loose clusters of small white flower heads produce dark dry fruits. Can form dense mats that reduce native seedling regeneration. The USDA risk assessment documents this pathway in Hawaii, including threats on Oahu; this is not a measured Kauai effect.
Kauaʻi evidence
Established island occurrence follows the Bishop Museum checklist. Diagnostic morphology follows Smithsonian Hawaiian Flora; accepted identity follows Kew WCVP. Generated imagery is not occurrence evidence. Proposed monitoring endpoints are not reported observations, measured effects or causal findings.
Names and classification
- Scientific name
- Ageratina riparia
- Common names
- spreading mist flower
- Hawaiian names
- Hāmākua pāmakani
- Other names
- Ageratina riparia · Hāmākua pāmakani · spreading mist flower · Ageratina repens · Ageratina ventillana · Eupatorium harrisii · Eupatorium riparium · Eupatorium ventillanum · Fleischmannia repens
- Record type
- Species
Kauaʻi occurrence and status
- Kauaʻi occurrence
- Recorded on Kauaʻi
- Origin
- Introduced
- Conservation status
- Not yet assessed
- Evidence date
- 2026-10-07
- Evidence limits
- Current extent and island effect sizes are unassessed. Public occurrence remains island-level only.
Habitat and ecology
- Habitats
- Moist disturbed forest · Riparian vegetation · Humid upland pasture
- Food and resource needs
- Not yet assessed
- Reproduction
- Local pollinators, flowering schedules, seedling establishment and recruitment rates are not independently assessed.
- Shelter
- Not yet assessed
- Growth form
- Shrub or subshrub
Threats and conservation
- Monitoring
- Ground-layer cover and occupied area; Native seedling recruitment in occupied and comparison plots; Shrub biomass and light availability. Proposed monitoring endpoints are not reported observations, measured effects or causal findings.
- Data gaps
- Current island population extent and trend · Quantified local environmental effects
Process and seasonal context
- Seasonal timing
- Not yet assessed
- Seasonal description
- Hāmākua pāmakani (Ageratina riparia) is recorded as an established shrub on Kauaʻi. A low, spreading subshrub with a creeping underground stem system and sprawling shoots roughly half a metre to one metre long. Narrow to elliptic leaves have sharp teeth. Loose clusters of small white flower heads produce dark dry fruits. Can form dense mats that reduce native seedling regeneration. The USDA risk assessment documents this pathway in Hawaii, including threats on Oahu; this is not a measured Kauai effect.