Taxon Report
Boechera rubicundula (Jeps.) Windham & Al-ShehbazMt. Day rockcress |
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Taxon Summary
Boechera rubicundula, commonly known as Mt. Day rockcress, is a perennial herb in the Brassicaceae that is found only in California. It occurs within Chaparral, growing at elevations from 1200 to 1200 meters. Boechera rubicundula is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Boechera rubicundula (Jeps.) Windham & Al-Shehbaz |
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Common Name: |
Mt. Day rockcress |
| Family: | Brassicaceae |
| Element Code: | PDBRA40100 |
| USDA Plants Symbol: | |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial herb |
| Blooming Period: Apr-May | Apr-May |
| Elevation: | 1200-1200 (3935-3935) |
| General Habitats: | Chaparral |
| Microhabitat: | Rocky, Slopes |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G1 |
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State Rank: |
S1 |
| State List: | None |
| Fed List: | None |
| Other Status: | |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 1 |
| Element Occurrence Ranks: | |
| Excellent (A) | 0 |
| Good (B) | 0 |
| Fair (C) | 0 |
| Poor (D) | 0 |
| None (X) | 0 |
| Unknown (U) | 1 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Santa Clara (SCL) | |
| Quads: Name (Quad Code) | |
| Mt. Day (3712146) | |
Threat List Data from the CNDDB
| Threat List Total: | 0 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 0 | % | |
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Notes
| One Known Occurrence (OKO); known only from the type collection on Mt. Day. |
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Threats: |
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Taxonomy: |
| Similar to B. arcuata and B. breweri ssp. breweri. Differs from B. arcuata in having spatulate to oblanceolate basal leaves, shorter fruiting pedicels with spreading trichomes, and shorter fruits; differs from B. breweri ssp. breweri in having taller stems with at least some 3-rayed trichomes, and slightly descending to horizontal fruiting pedicels with a predominance of 2-rayed trichomes. Windham and Al-Shehbaz (2007) “hypothesize that B. rubicundula is a reproductively competent, apomictic hybrid containing genomes from B. arcuata and B. breweri.” |
Selected References
| Proposed Addition to CRPR 1B.1, G1 / S1 (2011) |
| Flora of California 2:69 (1936) |
| Harvard Papers in Botany 11(2):257-274 (2007) |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 22 November 2025].