Taxon Report
Poa rhizomata Hitchc.timber blue grass |
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Species Description:
Poa rhizomata, commonly known as timber blue grass, is a perennial rhizomatous herb in the Poaceae that is found in California and elsewhere. It occurs within Lower montane coniferous forest, Subalpine coniferous forest, and Upper montane coniferous forest, growing at elevations from 520 to 2040 meters. Poa rhizomata is ranked 1B.3, Plants Rare, Threatened or Endangered in California and Elsewhere; Not very threatened in California.
Classification
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Scientific Name: |
Poa rhizomata Hitchc. |
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Common Name: |
timber blue grass |
| Family: | Poaceae |
| Element Code: | PMPOA4Z250 |
| USDA Plants Symbol: | PORH |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | perennial rhizomatous herb |
| Blooming Period: Apr-Jul | Apr-Jul |
| Elevation: | 520-2040 (1705-6695) |
| General Habitats: | Lower montane coniferous forest, Subalpine coniferous forest, Upper montane coniferous forest |
| Microhabitat: | Mesic, Serpentine (sometimes) |
| Microhabitat Details: | Semi-shaded moist slopes, small openings in forest |
Conservation Status
| CA Rare Plant Rank: | 1B.3 |
| Global Rank: | G3G4 |
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State Rank: |
S3S4 |
| 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: | 16 |
| Element Occurrence Ranks: | |
| Excellent (A) | 0 |
| Good (B) | 2 |
| Fair (C) | 0 |
| Poor (D) | 0 |
| None (X) | 0 |
| Unknown (U) | 14 |
| California Endemic: False | |
| California Counties and Islands: Name (Code) | |
| Shasta (SHA), Siskiyou (SIS), Trinity (TRI) | |
| Quads: Name (Quad Code) | |
| Bark Shanty Gulch (4112345), Billys Peak (4112227), Callahan (4112237), Chicken Hawk Hill (4112214), Condrey Mtn. (4112288), Cottonwood Peak (4112286), Dillon Mtn. (4112355), Eaton Peak (4112238), Etna (4112248), Greenview (4112258), Horse Creek (4112278), Kangaroo Mtn. (4112382), McKinley Mtn. (4112277), Somes Bar (4112344), Ukonom Lake (4112353), Ukonom Mtn. (4112354), Ycatapom Peak (4112217) | |
Threat List Data from the CNDDB
| Threat List Total: | 3 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 2 | 13 % | |
| Foot traffic/trampling | 1 | 6% |
| Grazing | 1 | 6% |
| Logging | 1 | 6% |
Notes
| Extremely rare and threatened in OR. |
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Threats: |
| Potentially threatened by logging, inappropriate grazing, trampling, and fire changes in fire regime. |
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Taxonomy: |
| Plants on ultramafic substrates in DNT Co. are referable to Poa piperi (previously treated as a taxonomic synonym of P. rhizomata). Other similar species are P. pratensis (nonnative naturalized in CA) and P. chambersii (OR endemic). |
Selected References
| Poa rhizomata Proposed Change from CRPR 4.3 to 1B.3 (2024) |
| Flora of California [Jepson] 1(3): 155 (1912) |
| USFS Potential Species of Conservation Concern Profile (2021) |
Citation
California Native Plant Society, Rare Plant Program. 2025. Rare Plant Inventory (online edition, v9.5.1). Website https://www.rareplants.cnps.org [accessed 20 January 2025].