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Bitterbrush

Purshia tridentata · Rosaceae · all Purshia records

Your local evidence lens

Separate evidence questions, never one approval badge

Set a ZIP to compare this record with state distribution, native range, USDA hardiness, and invasive records.

A genus split is not a placement verdict. Set a ZIP to read the local documented split.

1. Fire evidence and conditions

Fire evidence: Mixed evidence — location does not change the cited classification.
Fire-performance conditions: 1 condition stated in cited fire-evidence rows.
Fire ecology context: No section-reviewed fire-ecology context is normalized.
Placement evidence: 4 source placement records; source schemes remain separate.
Evidence regions: Ashland, Oregon; British Columbia; California; Colorado, California, and northeastern United States; Fremont County, Wyoming; Global; Lake Tahoe Basin, Nevada and California; Nevada / Great Basin; New Mexico; Utah / Intermountain West
Maintenance: No sourced horticultural maintenance assertion is normalized; fire-test conditions do not supply maintenance advice.

Typed publication scope: 6 scopes across 6 cited fire sources

Prohibited Flammable Plants (Ashland Municipal Code 9.04) · Official scoped edition
- City of Ashland (OR footprint); partial normalized coverage · 2026-08-26
  This is a City of Ashland adoption fact, not statewide Oregon guidance or an experimental flammability result. FireApproved publishes 24 taxonomy-safe owners as city-level regulatory context. It applies to new planting and propagation within 30 feet of structures, including structures on adjacent lots; it is not projected as a blanket removal order for every established listed plant.
Fremont County Firewise Plant List · Official scoped edition
- Fremont County (WY footprint); partial normalized coverage · 2011-02-25
  The source identifies itself as the Fremont County Firewise Plant List. FireApproved publishes its 92 exact source owners as Fremont County regional context. No methodology, current county endorsement, statewide Wyoming scope, or site-specific suitability is inferred.
FireWise Plant List for New Mexico · Official scoped edition
- NM; partial normalized coverage · 2003-10-08
  New Mexico Forestry Division publishes this as its FireWise Plant List for New Mexico. FireApproved accounts for all 140 printed rows and publishes 95 exact same-rank owners already represented in the directory; 29 exact taxa without an existing record, 14 unresolved spellings or higher-rank matches, one compound taxon cell, and one species row whose only apparent owner has an infraspecific printed identity remain held. Every published row retains the source's Y, N, ?, or blank elevation cells. Publication scope does not erase those elevation limits or establish suitability for every New Mexico site.
Home Landscaping Guide for Lake Tahoe and Vicinity (Ed. Bulletin 06-01) · Official scoped edition
- Lake Tahoe Basin (CA, NV footprint); partial normalized coverage · 2006-01-01
  Nevada Division of Forestry and University of Nevada Cooperative Extension publish Bulletin 06-01 for the Lake Tahoe Basin and vicinity. FireApproved publishes 83 exact rated owners as basin context across Nevada and California. Rough estimates are not statewide or site ratings.
A Compilation of Good Plant Choices for Nevada's High Fire Hazard Areas (SP-05-16) · Official scoped edition
- NV; partial normalized coverage · 2005-01-01
  University of Nevada Cooperative Extension compiled plants suited to Nevada climate zones and reported favorably by at least two upstream firewise lists. FireApproved publishes 126 exact source owners at Nevada publication scope. The source explicitly makes no independent flammability determination, so these rows remain corroborative.
Firewise Plants for Utah Landscapes (NR/FF/002) · Official scoped edition
- UT; partial normalized coverage · 2005-02-01
  Utah State University Extension states that this fact sheet selects examples for Utah landscapes and that they require proper placement and maintenance. FireApproved publishes 83 exact source owners at Utah publication scope. The table is not a site-specific planting clearance.

2. Why this plant is relevant here

State distribution: Documented in AZ, CA, CO, ID, MT, NE, NM, NV, OR, UT, WA, WY.
Native range: Current cited native range in AZ, CA, CO, ID, MT, NE, NM, NV, OR, UT, WA, WY.
Introduced / established: No introduced or established row is normalized; that does not prove native status.
USDA hardiness: Documented minimum 4a; no upper limit is documented.

3. Legal, ecological, and broader status

Legal-list status: Set a location for an exact legal-list result; source silence is not clearance.
Seed-list status: Set a location to compare the separate state noxious-weed seed layer.
Reported invasive here: No ecological invasive report is normalized; that does not prove noninvasiveness.
Broader regional context: Aggregate AK, HI, and L48 evidence is shown only as regional context, never as an exact-state finding.
Federal context: Federal designations remain separate from state legal-list results.

How to read this page

The status above is computed from the cited rows below: independent recommendations can support a fire-resistant result, an avoid row can produce keep-away, and disagreement stays visible as conflict. Placement notes preserve each source’s own scheme rather than translating unlike rules into one scale. This is evidence about a plant, not permission to plant it in every part of the defensible space; Zone 0 remains noncombustible.

Bitterbrush (Purshia tridentata) — Photo: (c) Tom Wainwright, some rights reserved (CC BY) (CC BY), via iNaturalist. Species-typical, not necessarily this cultivar.

Form: shrub
USDA hardiness: Minimum 4a; upper limit not documented
Mature height: ~3 ft
Water need: low
Current cited native range: AZ, CA, CO, ID, MT, NE, NM, NV, OR, UT, WA, WY
Grows in: AZ, CA, CO, ID, MT, NE, NM, NV +4
Rated in: Ashland, Oregon; British Columbia; California; Colorado, California, and northeastern United States +6
Family: Rosaceae
Evidence: 12 cited sources

Native and introduced range evidence

These are exact U.S. botanical-area records from the cited range source. Native and introduced describe biogeographic relationship, not fire performance or planting approval. Doubtful and extinct rows stay visible but do not count as current presence.

Current native

12

exact source areas

Current introduced

0

exact source areas

Qualified

0

doubtful or extinct source rows

12 native source areas · World Checklist of Vascular Plants, version 16 v16, as of 2026-06-04

Arizona (AZ)
California (CA)
Colorado (CO)
Idaho (ID)
Montana (MT)
Nebraska (NE)
New Mexico (NM)
Nevada (NV)
Oregon (OR)
Utah (UT)
Washington (WA)
Wyoming (WY)

The lossless worldwide derivative is retained once in the research corpus; object pages repeat only exact U.S. areas needed by the local lens. The JSON twin carries the same page assertions.

Plant hardiness evidence

These values describe the plant source. Your ZIP zone comes from the separate 2023 USDA Plant Hardiness Zone Map. Whole-zone values stay whole-zone, and a single unresolved value is not treated as a tolerance range. Different source boundaries stay separate: overlapping statements are compared independently, while only ranges with no shared zone are called a conflict.

USDA PLANTS Database — Plant Characteristics · record PUTR2 · PLANTS Help Document 2022; characteristics cache retrieved 2026-08-23 · as of 2026-08-26

Minimum 4a · no upper limit documented · half zone precision · derived containing band

Exact source measurement: -28°F; mapped only to its containing half-zone.

Source taxon: Purshia tridentata · source identifier match.

Source location: PlantCharacteristics record 90719, Temperature, Minimum (°F).

Conditions in the fire evidence

These describe tested or rated plant material. They are not horticultural maintenance instructions.

green: Cone calorimeter testing of vegetation — an update evidence row

Where its sources say to plant it

Placement rules below use each source's own distances or named zones, tied to its rating. They are not interchangeable with the directory's current Zone 0 guidance.

Prohibited Flammable Plants: new planting or propagation restricted within 30 ft of any structure [Ashland Municipal Code setback] (with its avoid rating)
Low-volume and slow-burning vegetation for planting on cl…: Table 5: Plants not considered suitable for use to reduce fire hazards [nord-green-brushland-clearing-performance] (mid-scale rating)
Home Landscaping Guide for Lake Tahoe and Vicinity: Fire Hazard column: high [tahoe-guide-2006] (with its avoid rating)
FireWise Plant List for New Mexico: PDF page 4, Shrubs, p4-r25 [nm-emnrd-firewise-table-row] (with its recommendation)

The evidence

Grouped by what each source concluded. Primary evidence rated the plant itself (a lab, field program, or original curation); corroboration compiled or republished another source's rating and resolves to its root lineage.

Avoids (2)

Prohibited Flammable Plants (Ashland Municipal Code 9.04) — City of Ashland, Oregon (Fire & Rescue / Weed Abatement) · 2025 · original source Primary evidence Regulation lineage: pnw590-tree

“prohibited flammable plant” · original source

The City of Ashland restricts new planting or propagation within 30 ft of any structure, including structures on adjacent lots (AMC 9.04).
Home Landscaping Guide for Lake Tahoe and Vicinity (Ed. Bulletin 06-01) — Nevada Division of Forestry / University of Nevada Cooperative Extension · Bulletin 06-01 (2006) · original source Corroboration Compilation lineage: unr-tree

“high — Bitterbrush — Purshia tridentata”

Table 1's Fire Hazard column prints “high” for this taxon. The guide calls the rating a rough estimate of potential flammability, not a result of scientific trials. Its footnote says plants that turn brown often become high fire hazards and tells readers to mow grasses and forbs when they begin to turn brown.

Mid-scale / conditional (2)

A Compilation of Good Plant Choices for Nevada's High Fire Hazard Areas (SP-05-16) — University of Nevada Cooperative Extension · SP-05-16 (2005) · original source Corroboration Compilation lineage: unr-tree

“listed by at least two sources; reviewers recorded disagreement”

Compilation marks: CSU 6.305, USU NR/FF/002.
Cone calorimeter testing of vegetation — an update — USDA Forest Service (White, Weise, Mackes & Dibble) · 2002 · original source Primary evidence Lab-tested lineage: usfs-fpl-cone-tree

“Measured; not in an author-named high or low relative-flammability group” · score 139 (green-PHRR-kW-m2) · condition: green

Table 4 reports 73% foliage moisture, green-sample PHRR 139 kW/m2, and dry-sample EHOC 17.1 MJ/kg.

Listed without a rating (4)

Low-volume and slow-burning vegetation for planting on clearings in California chaparral — USDA Forest Service, Pacific Southwest Forest and Range Experiment Station · PSW-124 · original source Primary evidence Field program

“Plants not considered suitable for use to reduce fire hazards”

Purshia tridentata: More cold but less drought tolerant than Purshia glandulosa.
FLAMITS: FLAMmability plant traiTS database — Dryad / Global Ecology and Biogeography · Dryad version 9 · original source Corroboration Trait database lineage: meta-aggregator

3 cited rows from this source; its identity, lineage and tier are stated once.
- “maximum energy flux (kW/m²): 139” · score 139 (FLAMITS — maximum energy flux (kW/m²))
  
  FLAMITS record 14136; Combustibility measurement; plant part leaves; fuel live; predrying no; device calorimeter; site White2002-2; sampling ND. Primary study White2002: White, R. H., Weise, D. R., Mackes, K., & Dibble, A. C. (2002). Cone calorimeter testing of vegetation--an update. Ninth International Conference on Electrical and Electronic Products. Columbus, Ohio, USA.
- “calorific value (kcal/kg): 4084.26” · score 4084.26 (FLAMITS — calorific value (kcal/kg))
  
  FLAMITS record 14189; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site White2002-2; sampling ND. Primary study White2002: White, R. H., Weise, D. R., Mackes, K., & Dibble, A. C. (2002). Cone calorimeter testing of vegetation--an update. Ninth International Conference on Electrical and Electronic Products. Columbus, Ohio, USA.
- “calorific value (kcal/kg): 4084.26” · score 4084.26 (FLAMITS — calorific value (kcal/kg))
  
  FLAMITS record 14280; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site White2002-2; sampling ND. Primary study White2002: White, R. H., Weise, D. R., Mackes, K., & Dibble, A. C. (2002). Cone calorimeter testing of vegetation--an update. Ninth International Conference on Electrical and Electronic Products. Columbus, Ohio, USA.

Fire-resistant shrubs instead

Red-osier dogwood
Cornus sericea

Creeping holly
Berberis repens

Rocky Mountain maple
Acer glabrum

Wood’s rose
Rosa woodsii

Four-wing Saltbush
Atriplex canescens

Sumac
Rhus trilobata

Fire-resistant shrubs listed above

Last verified 2026-08-23. JSON (CC BY 4.0)

Profiles: USDA PLANTS · GBIF · iNaturalist · Wikidata · ITIS

Purshia tridentata (Bitterbrush). FireApproved. https://fireapproved.com/plants/purshia-tridentata/. Last verified 2026-08-23.