Family: Acanthaceae
Origin, Description & Uses
Ruellia longepetiolata (water bluebell) is native to Mexico, where it occurs in regions such as Querétaro, Veracruz, and Puebla. It is an attractive flowering plant often grown for its ornamental value, producing showy blue to purple, trumpet-shaped blooms and lush green foliage. In landscaping, it is sometimes used in tropical and subtropical gardens, including pond edges and moist garden areas, where its colorful flowers and fast-growing habit are appreciated.
Risks & Threats
In Hawaiʻi, water bluebell is already naturalized on Kauaʻi and Oʻahu. This species possesses traits that are cause for concern, including vigorous growth and the ability to spread beyond intended plantings. It can form dense stands that compete with and displace native vegetation in wet and riparian habitats, potentially altering ecosystem structure in sensitive tropical island environments. Because it is naturalized and capable of further spread, it could detrimentally impact tropical island ecosystems if left unmanaged. Where available, choosing low-risk or native alternatives is strongly recommended. In areas where it is not yet widely established, avoiding planting and actively managing existing populations can help minimize further spread and ecological impacts.
High Risk Traits:
- Naturalized in La Réunion, Australia, and Okinawa
- Congeneric weed (Ruellia brittoniana) is invasive in Florida
- Introduced intentionally as an ornamental ground cover
- Shade tolerant (grows in shaded creeksides)
- Produces viable seed
- Self-compatible
- Reproduces vegetatively via rhizomes and clump division
- Propagules dispersed by water and people
- Tolerates cultivation and mutilation
Low Risk Traits:
- Not a reported weed (garden, agricultural, or environmental)
- No spines, thorns, or burrs
- Not parasitic, toxic, or allelopathic
- No serious pests or pathogens
- No fire hazard (herbaceous)
- Low seed production (~12 seeds per capsule)
- No wind, bird, or external animal dispersal
