- Also Known As: Yellow Evening Primrose, Missouri Evening Primrose, Fluttermill
- Botanical Name: O. macrocarpa
- Plant Type: Perennial
- Light Requirement: Full Sun
- Water Demand: Low, Medium
- Landscape Use: Rock Garden, Moon Garden
- Ornamental Value: Yellow
- Native/Adapted: Native
- Wildlife Value: Butterflies (nectar source), Birds, Hummingbirds
- Season: Spring, Summer
- Deciduous/Evergreen: Deciduous
- Plant Form: Spreading
- Plant Spread: 2'
- Plant Height: 1'
Description4-inch bright yellow cup-shaped flowers. Mounding foliage. Flowers open in the evening and stay open through the night. Buds are pinkish green and speckled. Deadhead to encourage longer flowering.