Family: Nyctaginaceae

Origin, Description & Uses
Mirabilis jalapa (four-o’clock) is a flowering plant native to Mexico and extending south to Nicaragua. It is a fast-growing perennial herb known for its brightly colored, trumpet-shaped flowers that often open in the late afternoon—hence the common name “four-o’clock.” Flowers can appear in shades of pink, red, yellow, white, or multi-colored combinations on the same plant. It is widely cultivated around the world as an ornamental garden plant because of its long blooming period, ease of growth, and ability to attract hummingbirds, butterflies, and moths. In some regions, it has also been used traditionally in herbal remedies and as a natural dye source, though its primary use today is ornamental landscaping.

Risks & Threats
In Hawaiʻi, Mirabilis jalapa is naturalized on Kuaihelani (Midway Atoll), Kauaʻi, Oʻahu, Molokaʻi, Lānaʻi, Maui, and Hawaiʻi Island, demonstrating its ability to spread beyond cultivation and establish in a wide range of environments. This species produces abundant seeds and can form persistent populations in disturbed areas, roadsides, and open habitats, where it may compete with native plants for space and resources. Its ability to thrive in coastal and dry conditions makes it particularly concerning for sensitive tropical island ecosystems. While it is still often planted for its ornamental value, its spread across multiple Hawaiian Islands shows it possesses traits that are cause for concern. When possible, choosing a low-risk or native alternative is recommended to help protect Hawaiʻi’s unique ecosystems from further plant invasions.

High Risk Traits:

• Broad climate suitability (USDA zones 7–11)
  
• Native or naturalized in tropical/subtropical regions
  
• History of repeated introductions outside native range
  
• Naturalized outside native range (e.g., Hawaii)
  
• Garden/amenity/disturbance weed
  
• Congeneric weed (Mirabilis nyctaginea is a noxious weed)
  
• Toxic to animals and humans (roots, seeds)
  
• Shade tolerant
  
• Tolerates wide range of soil conditions (acidic to alkaline)
  
• Geophyte (tuberous roots, allows vegetative reproduction)
  
• Produces viable seed
  
• Self-compatible
  
• Reproduces by vegetative fragmentation
  
• Minimum generative time = 1 year
  
• Propagules dispersed intentionally by people (ornamental, medicinal)
  
• Propagules water-dispersed
  
• Tolerates mutilation/cultivation (tubers can be divided)

Low Risk Traits:

• No spines, thorns, or burrs