Taxon Report
Neostapfia colusana (Davy) DavyColusa grass |
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Taxon Summary
Neostapfia colusana, commonly known as Colusa grass, is a annual herb in the Poaceae that is found only in California. It occurs within Vernal pools, growing at elevations from 5 to 200 meters. Neostapfia colusana is ranked 1B.1, Plants Rare, Threatened or Endangered in California and Elsewhere; Seriously threatened in California.Classification
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Scientific Name: |
Neostapfia colusana (Davy) Davy |
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Common Name: |
Colusa grass |
| Family: | Poaceae |
| Element Code: | PMPOA4C010 |
| USDA Plants Symbol: | NECO2 |
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Synonyms/Other Names: |
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Ecology and Life History
| Lifeform: | annual herb |
| Blooming Period: May-Aug | May-Aug |
| Elevation: | 5-200 (15-655) |
| General Habitats: | Vernal pools |
| Microhabitat: | |
| Microhabitat Details: |
Conservation Status
| CA Rare Plant Rank: | 1B.1 |
| Global Rank: | G1 |
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State Rank: |
S1 |
| State List: | CE |
| Fed List: | FT |
| Other Status: | |
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CRPR Changes: |
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Occurrence Data from the CNDDB
| Total Occurrences: | 66 |
| Element Occurrence Ranks: | |
| Excellent (A) | 3 |
| Good (B) | 13 |
| Fair (C) | 21 |
| Poor (D) | 3 |
| None (X) | 21 |
| Unknown (U) | 5 |
| California Endemic: True | |
| California Counties and Islands: Name (Code) | |
| Colusa (COL)*, Glenn (GLE), Merced (MER), Solano (SOL), Stanislaus (STA), Yolo (YOL) | |
| Quads: Name (Quad Code) | |
| Arena (3712036), Atwater (3712035), Bachelor Valley (3712087), Cooperstown (3712065), Dozier (3812137), El Nido (3712024)*, Haystack Mtn. (3712043), Knights Ferry (3712076), Logandale (3912242), Merced (3712034), Montpelier (3712056), Owens Reservoir (3712032), Paulsell (3712066), Planada (3712033), Princeton (3912241)*, Sandy Mush (3712025), Saxon (3812146), Turlock Lake (3712055), Turner Ranch (3712026), Waterford (3712067)*, Yosemite Lake (3712044) | |
Threat List Data from the CNDDB
| Threat List Total: | 16 | |
| EOs with Threat Listed: | Total EOs | % of EOs |
| 63 | 95 % | |
| Grazing | 54 | 81% |
| Agriculture | 24 | 36% |
| Non-native plant impacts | 16 | 24% |
| Foot traffic/trampling | 10 | 15% |
| Altered flood/tidal/hydrologic regime | 9 | 13% |
| Other | 7 | 10% |
| Disking | 5 | 7% |
| Dam/Inundation | 4 | 6% |
| Erosion/runoff | 3 | 4% |
| Biocides | 2 | 3% |
| ORV activity | 2 | 3% |
| Pollution | 1 | 1% |
| Road/trail construction/maint. | 1 | 1% |
| Surface water diversion | 1 | 1% |
| Development | 1 | 1% |
| Non-native animal impacts | 1 | 1% |
Notes
| Threatened by agriculture, development, overgrazing, hydrological alterations, non-native plants, and habitat fragmentation and loss. See Erythea 6:110-113 (1898) for original description, Fremontia 4(3):22-23 (1976) for species account and habitat information, and Conservation Genetics (2011) pp. 1-14 for population genetic information. |
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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 17 November 2025].