Taxon Report
Ceanothus sonomensis J.T. HowellSonoma ceanothus |
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Taxon Summary
Ceanothus sonomensis, commonly known as Sonoma ceanothus, is a perennial evergreen shrub in the Rhamnaceae that is found only in California. It occurs within Chaparral (sandy, serpentine, and volcanic), growing at elevations from 215 to 800 meters. Ceanothus sonomensis is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.Classification
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Scientific Name: |
Ceanothus sonomensis J.T. Howell |
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Common Name: |
Sonoma ceanothus |
| Family: | Rhamnaceae |
| Element Code: | PDRHA04420 |
| USDA Plants Symbol: | CESO |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial evergreen shrub |
| Blooming Period: Feb-Apr | Feb-Apr |
| Elevation: | 215-800 (705-2625) |
| General Habitats: | Chaparral |
| Microhabitat: | |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.2 |
| Global Rank: | G2 |
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State Rank: |
S2 |
| State List: | None |
| Fed List: | None |
| Other Status: | SB_SBBG |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 30 |
| Element Occurrence Ranks: | |
| Excellent (A) | 3 |
| Good (B) | 1 |
| Fair (C) | 0 |
| Poor (D) | 1 |
| None (X) | 0 |
| Unknown (U) | 25 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Lake (LAK), Napa (NAP), Sonoma (SON) | |
| Quads: Name (Quad Code) | |
| Aetna Springs (3812264), Calistoga (3812255), Chiles Valley (3812253), Detert Reservoir (3812265), Glen Ellen (3812235), Kenwood (3812245), Rutherford (3812244), Santa Rosa (3812246), Sonoma (3812234), St. Helena (3812254), Walter Springs (3812263) | |
Threat List Data from the CNDDB
| Threat List Total: | 4 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 3 | 10 % | |
| Improper burning regime | 2 | 6% |
| Other | 1 | 3% |
| Road/trail construction/maint. | 1 | 3% |
| Development | 1 | 3% |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 4 November 2025].