Family: Lamiaceae
Origin, Description & Uses
Rotheca serrata (beetle killer, blue fountain bush) is native to the Indian Subcontinent, southern China, and western Malesia. It is a fast-growing, tropical shrub or small tree known for its attractive ornamental appearance. The plant produces striking clusters of blue to violet, tubular flowers that are highly attractive to pollinators such as butterflies and bees. Because of its showy blooms and lush growth habit, it is sometimes used in tropical and subtropical gardens and landscapes as an ornamental hedge or accent plant.
Risks & Threats
Although Rotheca serrata is not known to be naturalized in Hawaiʻi, it does possess traits that are cause for concern, including vigorous growth, prolific flowering, and successful reproduction via seed production. In suitable climates, these characteristics can allow related species to spread beyond intended plantings. Ongoing evaluation is needed to determine whether this species could establish in Hawaiʻi and potentially impact native ecosystems. Caution is recommended to ensure it does not escape cultivation or negatively affect Hawaii’s natural habitats.
High Risk Traits:
- Elevation range exceeds 1000 m, demonstrating environmental versatility
- Thrives in tropical climates
- Naturalizing on Oahu, Hawaiian Islands (confirmation needed) and naturalized in Madagascar; Mauritius; Reunion
- Identified as a weed, but impacts unspecified
- Shade-tolerant
- Seeds dispersed by birds and intentionally by people
- Limited ecological information makes accurate risk prediction difficult
Low Risk Traits:
- Unarmed (no spines, thorns or burrs)
- Ornamental and medicinal uses
