Stemless Evening Primrose
Oenothera triloba
- Native to:
- Mexico, United States
Barton, William P. C.
Taxonomy
- Division:
- Magnoliophyta | - Flowering plants
- Family:
- Onagraceae
- Genus:
- Oenothera
- Species:
- Oenothera triloba
- USDA Symbol:
- OETR2
Growth Characteristics
- Life Cycle:
- Annual | Biennial
- Growth Habit:
- Forb/herb
- Height:
- 30 cm
- Light Requirements:
- Full Sun
- Drought Tolerance:
- High
- Bloom Months:
- apr,may,jun
- Bloom Colors:
- yellow
Wildlife Benefits
- Bees:
- ★☆☆☆☆ Documented bee visitation (GBIF)
Keystone Species Ranking
- Caterpillar Keystone:
- ★★☆☆☆ Butterfly & moth species supported by this genus (NWF)
- Pollen Specialist Bee Keystone:
- ★★★☆☆ Native pollen specialist bee species supported by this genus (NWF)
Garden & Ecology Notes
- Wildlife Value:
- bees, moths
- Deer Resistant:
- Yes
- Fragrant:
- Yes
Soil Requirements
- Soil Type:
- sandy, well-drained, nutrient-poor soil
- pH:
- 6.0 - 7.5 (slightly acidic to neutral)
- Drainage:
- excellent drainage required
- Moisture:
- dry to moderate
- Notes:
- thrives in open, sunny habitats
Propagation & Germination
- Stratification:
- Cold/moist stratification required — 30–60 days
- Germination Time:
- 14–30 days
- Notes:
- Seeds germinate best with light exposure. Cool temperatures improve germination rates.
The above propagation data sourced from Claude AI
Pre-treatment: Cold-moist stratification for 30 days at 1–5°C (34–41°F).
Notes: Seeds require cold-moist stratification for 30 days before germination.
Source: Claude AI
ORGHPS Germination Guide: Sow @ 20C. Germinates within 3 months.