Taxon Report
Plagiobothrys diffusus (Greene) Jtn.San Francisco popcornflower |
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Taxon Summary
Plagiobothrys diffusus, commonly known as San Francisco popcornflower, is a annual herb in the Boraginaceae that is found only in California. It occurs within Coastal prairie, and Valley and foothill grassland, growing at elevations from 60 to 360 meters. Plagiobothrys diffusus is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Plagiobothrys diffusus (Greene) Jtn. |
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Common Name: |
San Francisco popcornflower |
| Family: | Boraginaceae |
| Element Code: | PDBOR0V080 |
| USDA Plants Symbol: | |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | annual herb |
| Blooming Period: Mar-Jun | Mar-Jun |
| Elevation: | 60-360 (195-1180) |
| General Habitats: | Coastal prairie, Valley and foothill grassland |
| Microhabitat: | |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G1Q |
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State Rank: |
S1 |
| State List: | CE |
| Fed List: | None |
| Other Status: | SB_UCSC |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 17 |
| Element Occurrence Ranks: | |
| Excellent (A) | 2 |
| Good (B) | 5 |
| Fair (C) | 6 |
| Poor (D) | 1 |
| None (X) | 1 |
| Unknown (U) | 2 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Alameda (ALA), San Benito (SBT), San Francisco (SFO)*, San Mateo (SMT), Santa Cruz (SCR) | |
| Quads: Name (Quad Code) | |
| Ano Nuevo (3712213), Davenport (3712212), Felton (3712211), Franklin Point (3712223), Laurel (3712118), Oakland East (3712272), San Francisco North (3712274)*, San Juan Bautista (3612175), Santa Cruz (3612281), Watsonville West (3612187) | |
Threat List Data from the CNDDB
| Threat List Total: | 12 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 16 | 94 % | |
| Non-native plant impacts | 10 | 58% |
| Development | 9 | 52% |
| Other | 6 | 35% |
| Grazing | 5 | 29% |
| Recreational use (non-ORV) | 3 | 17% |
| Road/trail construction/maint. | 2 | 11% |
| Wood cutting or brush clearing | 2 | 11% |
| ORV activity | 2 | 11% |
| Improper burning regime | 1 | 5% |
| Erosion/runoff | 1 | 5% |
| Altered flood/tidal/hydrologic regime | 1 | 5% |
| Biocides | 1 | 5% |
Notes
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Threatened by development and non-native plants. Possibly threatened by grazing and vehicles. Identification difficult; taxonomic work needed. See P. reticulatus |
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Threats: |
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Taxonomy: |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 13 November 2025].