Taxon Report
Oenothera deltoides Torr. & Frem. ssp. howellii (Munz) W. KleinAntioch Dunes evening-primrose |
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Taxon Summary
Oenothera deltoides ssp. howellii, commonly known as Antioch Dunes evening-primrose, is a perennial herb in the Onagraceae that is found only in California. It occurs within Inland dunes, growing at elevations from 0 to 30 meters. Oenothera deltoides ssp. howellii is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Oenothera deltoides Torr. & Frem. ssp. howellii (Munz) W. Klein |
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Common Name: |
Antioch Dunes evening-primrose |
| Family: | Onagraceae |
| Element Code: | PDONA0C0B4 |
| USDA Plants Symbol: | OEDEH |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial herb |
| Blooming Period: Mar-Sep | Mar-Sep |
| Elevation: | 0-30 (0-100) |
| General Habitats: | Inland dunes |
| Microhabitat: | |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G5T1 |
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State Rank: |
S1 |
| State List: | CE |
| Fed List: | FE |
| Other Status: | SB_CalBG/RSABG; SB_UCBG |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 8 |
| Element Occurrence Ranks: | |
| Excellent (A) | 0 |
| Good (B) | 2 |
| Fair (C) | 2 |
| Poor (D) | 2 |
| None (X) | 1 |
| Unknown (U) | 1 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Contra Costa (CCA), Sacramento (SAC) | |
| Quads: Name (Quad Code) | |
| Antioch North (3812117), Clayton (3712188), Jersey Island (3812116), Walnut Creek (3712281) | |
Threat List Data from the CNDDB
| Threat List Total: | 7 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 7 | 88 % | |
| Non-native plant impacts | 5 | 62% |
| Other | 4 | 50% |
| Development | 2 | 25% |
| Mining | 2 | 25% |
| Biocides | 1 | 12% |
| Foot traffic/trampling | 1 | 12% |
| Recreational use (non-ORV) | 1 | 12% |
Notes
| Occurrences from SAC Co. (480C) and CCA Co. (481C) are introduced. Seriously threatened by mining, agriculture, industrial development, and non-native plants. Recovery work in progress. Protected in part at Antioch Dunes NWR (USFWS). See Aliso 2:81 (1949) for original description, Four Seasons 3(1):2-4 (1969) for threat information, and Biological Conservation 65:257-278 (1993) for population biology. |
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Threats: |
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Taxonomy: |
Selected References
| Recovery Plan for Oenothera deltoides ssp. howellii (Antioch Dunes evening-primrose) (1984) |
| Recovery Plan Amendment for Oenothera deltoides ssp. howellii (Antioch Dunes evening-primrose) (1984) |
| Critical habitat for Oenothera deltoides ssp. howellii |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 9 November 2025].