Taxon Report
Chorizanthe robusta Parry var. robustarobust spineflower |
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Taxon Summary
Chorizanthe robusta var. robusta, commonly known as robust spineflower, is a annual herb in the Polygonaceae that is found only in California. It occurs within Chaparral (maritime), Cismontane woodland (openings), Coastal dunes, and Coastal scrub, growing at elevations from 3 to 300 meters. Chorizanthe robusta var. robusta is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Chorizanthe robusta Parry var. robusta |
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Common Name: |
robust spineflower |
| Family: | Polygonaceae |
| Element Code: | PDPGN040Q2 |
| USDA Plants Symbol: | CHROR |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | annual herb |
| Blooming Period: Apr-Sep | Apr-Sep |
| Elevation: | 3-300 (10-985) |
| General Habitats: | Chaparral, Cismontane woodland, Coastal dunes, Coastal scrub |
| Microhabitat: | Gravelly (sometimes), Sandy (sometimes) |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G2T1 |
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State Rank: |
S1 |
| State List: | None |
| Fed List: | FE |
| Other Status: | |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 20 |
| Element Occurrence Ranks: | |
| Excellent (A) | 2 |
| Good (B) | 5 |
| Fair (C) | 2 |
| Poor (D) | 0 |
| None (X) | 5 |
| Unknown (U) | 6 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Alameda (ALA)*, San Francisco (SFO), San Mateo (SMT)*, Santa Clara (SCL)*, Santa Cruz (SCR) | |
| Quads: Name (Quad Code) | |
| Calaveras Reservoir (3712147), Felton (3712211), Laurel (3712118)*, Los Gatos (3712128)*, Milpitas (3712148), Moss Landing (3612177), Oakland East (3712272)*, Oakland West (3712273), San Francisco South (3712264)*, San Jose East (3712137), San Jose West (3712138)*, San Leandro (3712262), Santa Cruz (3612281), Soquel (3612188), Watsonville West (3612187) | |
Threat List Data from the CNDDB
| Threat List Total: | 8 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 16 | 80 % | |
| Development | 7 | 35% |
| Non-native plant impacts | 5 | 25% |
| Recreational use (non-ORV) | 5 | 25% |
| Other | 3 | 15% |
| Road/trail construction/maint. | 2 | 10% |
| Wood cutting or brush clearing | 1 | 5% |
| ORV activity | 1 | 5% |
| Logging | 1 | 5% |
Notes
| Most populations extirpated, and now known from only six extended occurrences. Threatened by development, recreation, mining, and non-native plants. See C. robusta in The Jepson Manual. See Phytologia 66(2):130-131 (1989) for taxonomic treatment, and Fremontia 24(4):8-11 (1996) for taxonomic discussion. |
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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 9 November 2025].