Taxon Report
Polyctenium williamsiae RollinsWilliams' combleaf |
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Taxon Summary
Polyctenium williamsiae, commonly known as Williams' combleaf, is a perennial herb in the Brassicaceae that is found in California and elsewhere. It occurs within Great Basin scrub, Marshes and swamps, Pinyon and juniper woodland, Playas, and Vernal pools, growing at elevations from 1347 to 2700 meters. Polyctenium williamsiae is ranked 1B.2, Plants Rare, Threatened or Endangered in California and Elsewhere; Moderately threatened in California.Classification
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Scientific Name: |
Polyctenium williamsiae Rollins |
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Common Name: |
Williams' combleaf |
| Family: | Brassicaceae |
| Element Code: | PDBRA23030 |
| USDA Plants Symbol: | POWI |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial herb |
| Blooming Period: Mar-Jul | Mar-Jul |
| Elevation: | 1347-2700 (4420-8860) |
| General Habitats: | Great Basin scrub, Marshes and swamps, Pinyon and juniper woodland, Playas, Vernal pools |
| Microhabitat: | Lake Margins, Sandy, Volcanic |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.2 |
| Global Rank: | G2Q |
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State Rank: |
S1 |
| State List: | None |
| Fed List: | None |
| Other Status: | BLM_S; USFS_S |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 6 |
| Element Occurrence Ranks: | |
| Excellent (A) | 0 |
| Good (B) | 3 |
| Fair (C) | 0 |
| Poor (D) | 0 |
| None (X) | 0 |
| Unknown (U) | 3 |
| California Endemic: False | |
| California Counties and Islands: Name (Code) | |
| Lassen (LAS), Mono (MNO) | |
| Quads: Name (Quad Code) | |
| Anderson Mtn. (4012085), Aurora (3811838), Cedar Hill (3811827), Dome Hill (3811931), Shaffer Mtn. (4012043), West of Huntoon Spring (3811816) | |
Threat List Data from the CNDDB
| Threat List Total: | 6 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 5 | 83 % | |
| Grazing | 4 | 66% |
| Foot traffic/trampling | 2 | 33% |
| Agriculture | 1 | 16% |
| Mining | 1 | 16% |
| Road/trail construction/maint. | 1 | 16% |
| Surface water diversion | 1 | 16% |
Notes
| Threatened by grazing and trampling. Possibly threatened by recreational activities. State-listed as Critically Endangered in NV. A synonym of P. fremontii in TJM 2. See Journal of the Arnold Arboretum 64:508 (1983) for original description, and Intermountain Flora 2B:416-419 (2005) for taxonomic treatment. |
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Threats: |
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Taxonomy: |
Selected References
| CRPR List Deletion on 2012-02-08 |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 7 December 2025].