Family: Onagraceae

Origin, Description & Uses
Oenothera stricta subsp. stricta (evening primrose) is native to coastal and inland regions of the Desventurados Islands and extends from Chile to southern Argentina. It is a hardy flowering herb that typically grows in open, sunny environments and is recognized for its showy yellow flowers that open in the evening, a characteristic trait of evening primroses. The plant often forms low rosettes before sending up flowering stems and is sometimes grown as an ornamental for its bright blooms and ability to attract pollinators such as moths and bees.

Risks & Threats
In Hawaiʻi, this species is naturalized and relatively common in open and disturbed sites, especially along roadsides at mid- to high-elevations (approximately 1,200–2,740 m) on East Maui and the Island of Hawaiʻi. It was first collected on Maui in 1919, indicating a long-established presence in the islands. While it may appear harmless in disturbed landscapes, it possesses traits that are cause for concern, including its ability to spread in open habitats and persist in challenging conditions. As a naturalized species, it could detrimentally impact tropical island ecosystems by competing with native vegetation and altering habitat structure in sensitive upland environments. Choosing low-risk or native plant alternatives is recommended when such options are available.

High Risk Traits:

• Elevation range exceeds 1000 m, and able to grow in >5 hardiness zones, demonstrating environmental versatility
  
• Naturalized in locations with subtropical climates (possibly only at higher elevations)
  
• Widely naturalized
  
• A disturbance-adapted weed with possible negative environmental effects
  
• Tolerates many soil types
  
• Self-compatible
  
• Able to reach maturity in <1 year
  
• Seeds dispersed intentionally and unintentionally by people, by wind, and water
  
• May form a persistent seed bank
  
• Older plants tolerant of glyphosate

Low Risk Traits:

• May only threaten higher elevations in tropical and subtropical regions
  
• Unarmed (no spines, thorns or burrs)
  
• Provides fodder for livestock
  
• Ornamental
  
• Beneficial to pollinators
  
• Requires full sun
  
• Not reported to spread vegetatively
  
• Herbicides may provide effective control of younger plants