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United States / Grow / black locust

black locust (Robinia pseudoacacia)
Photo: (c) Sandy Wolkenberg, some rights reserved (CC BY) (CC BY), via iNaturalist. Species-typical, not necessarily this cultivar.

black locust

Robinia pseudoacacia · Fabaceae · all Robinia records · also called Purple Robe locust · Wikipedia

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Black locust is rated fire resistant overall, but one New Zealand assessment conflicts with five favorable U.S.

assessments.

OSU, WSU, and University of Idaho Extension and the Washington State Department of Natural Resources list black locust as fire resistant. North Carolina State University and its partners give it the lowest band on a four-level flammability scale. Ohio State University Extension rates it L, the second-lowest band on its five-point scale, while Virginia Cooperative Extension and Virginia Tech assign L on their three-point scale. Together, these U.S. findings favor the tree.

Fire and Emergency New Zealand reaches the opposing result. Its seven-level classification, grounded in shoot-flammability testing at Lincoln University, places black locust in the moderate-high band. The agency also includes it on a high-flammability environmental-weeds list. This laboratory-based assessment differs from the expert-curated and compiled U.S. guidance in method, scale, and regional premise, though those differences do not establish why the findings conflict.

The balance supports calling black locust fire resistant, but not without qualification. It is a roughly 50-foot tree native to the southeastern and northeastern United States, and its favorable ratings come from several U.S. regions. The New Zealand result means the fire-resistant label is not universal and should not be treated as a guarantee of how the tree will burn under every condition.

Form
tree
Mature height
~50 ft
Water need
moderate
Rated in
Arizona above 3,000 feet / interior Southwest; Arkansas; Catalonia, Spain; Global +16
On this lot

1. Fire evidence and conditions

Fire evidence
Fire-resistant — location does not change the cited classification.
Fire-performance conditions
2 conditions stated in cited fire-evidence rows.
Placement evidence
6 source placement records; source schemes remain separate.
Evidence regions
Arizona above 3,000 feet / interior Southwest; Arkansas; Catalonia, Spain; Global; Japan; Montana / Northern Rockies; NC; Nevada / Great Basin; New Zealand; North Carolina; North Carolina / southeastern US; Northeast China; OR/WA/ID; Ohio / Midwest; Oregon; Valencia, Spain / western Mediterranean; Virginia / Mid-Atlantic; eastern US; eastern WA; north-eastern and mid-Atlantic United States
Typed publication scope: 9 scopes across 9 cited fire sources
  • Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter · Official scoped edition
    • Northeastern and mid-Atlantic study sites (ME, MD, MA, NY, VA footprint); partial normalized coverage · 2007-08-20

      The authors collected foliage and twigs across study sites in Maine, Maryland, Massachusetts, New York, and Virginia, then conditioned and tested the samples in a cone calorimeter. FireApproved publishes 37 exact source owners only as multi-state laboratory context. The source does not establish that every taxon was sampled in every named state, whole-plant behavior, landscape suitability, or state planting guidance.

  • Fire-Resistant Plants for Montana Landscapes (MontGuide MT200101AG) · Official scoped edition
    • MT; partial normalized coverage · 2022-04-01

      The April 2022 MontGuide explicitly presents fire-resistant species adapted to Montana. FireApproved publishes 92 exact plant records from the source while retaining excluded genus, family, and unresolved rows; the guide itself says not every listed species grows in every part of the state.

  • Fire-Resistant Landscaping in North Carolina (AG-874) · Official scoped edition
    • NC; complete normalized coverage · 2025-03-26

      The complete three-table AG-874 plant list is explicitly for North Carolina and contains 202 low-, medium-, or high-flammability rows. FireApproved accounts for all source rows under its strict taxonomy and lineage rules; source scope does not establish local suitability at a particular North Carolina site.

  • Firewise Landscaping (OSU Extension Bulletin 921) · Official scoped edition
    • OH; partial normalized coverage · 2006-03-01

      Ohio State University Extension Bulletin 921 is an Ohio publication that describes Ohio fire seasons and landscape conditions and labels nativity to Ohio. FireApproved publishes 352 exact source-owning plant records from its eight rated tables. This historical publication scope does not assert current extension endorsement or that a listed plant suits every Ohio site.

  • Fire-Resistant Plants for Home Landscapes (PNW 590) · Official scoped edition
    • ID, OR, WA; partial normalized coverage · 2023-10-01

      The October 2023 joint Pacific Northwest Extension publication explicitly names Oregon, Washington, and Idaho and publishes more than 150 plant profiles. FireApproved has normalized 155 exact plant records from the source; publication scope does not assert that every listed plant suits every site within the three states.

  • FIREWISE Plant Materials for 3,000 ft. and Higher Elevations (AZ1289) · Official scoped edition
    • Arizona at or above 3,000 feet (AZ footprint); partial normalized coverage · 2011-12-01

      AZ1289 is explicitly limited to Arizona elevations of 3,000 feet and higher. FireApproved publishes 69 exact owners as regional Arizona context, retaining every water and elevation condition. It is never promoted to statewide low-desert guidance or an independent Tier 1 vote.

  • 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.

  • Virginia Firescapes — Firewise Landscaping for Woodland Homes (430-300) · Official scoped edition
    • VA; partial normalized coverage · 2009-04-15

      Virginia Cooperative Extension's publication opens with Virginia wildfire conditions, identifies its Virginia Firewise Landscaping Task Force, and labels plants native to Virginia. FireApproved publishes 306 exact source owners. Publication scope does not establish parcel suitability or current endorsement of this archived 2009 list.

  • Fire-Resistant Plants for Eastern Washington · Official scoped edition
    • Eastern Washington (WA footprint); partial normalized coverage

      Washington DNR publishes the guide for Eastern Washington and says it compiles plants from other Firewise documents that are likely to thrive there. FireApproved publishes 46 exact owners only as eastern Washington context. The rows are corroborative, not empirical or statewide.

2. Why this plant is relevant here

State distribution
Documented in AL, AR, AZ, CA, CO, CT, DC, DE, FL, GA, IA, ID, IL, IN, KS, KY, LA, MA, MD, ME, MI, MN, MO, MS, MT, NC, ND, NE, NH, NJ, NM, NV, NY, OH, OK, OR, PA, RI, SC, SD, TN, TX, UT, VA, VT, WA, WI, WV, WY.
Native range
Current cited native range in AL, GA, KY, MD, NC, PA, SC, TN, VA, WV.
Introduced / established
39 sourced range or established records. This is not an invasive warning.
USDA hardiness
2 applicable cited hardiness statements overlap but have different boundaries; compare each complete source row.

3. Legal, ecological, and broader status

Legal-list status
4 legal-list records; the Place chip matches exact scope.
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.

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

10

exact source areas

Current introduced

39

exact source areas

Qualified

0

doubtful or extinct source rows

10 native source areas · World Checklist of Vascular Plants, version 16 v16, as of 2026-06-04
  • Alabama (AL)
  • Georgia (GA)
  • Kentucky (KY)
  • Maryland (MD)
  • North Carolina (NC)
  • Pennsylvania (PA)
  • South Carolina (SC)
  • Tennessee (TN)
  • Virginia (VA)
  • West Virginia (WV)
39 introduced source areas · World Checklist of Vascular Plants, version 16 v16, as of 2026-06-04
  • Arkansas (AR)
  • Arizona (AZ)
  • California (CA)
  • Colorado (CO)
  • Connecticut (CT)
  • District of Columbia (DC)
  • Delaware (DE)
  • Florida (FL)
  • Iowa (IA)
  • Idaho (ID)
  • Illinois (IL)
  • Indiana (IN)
  • Kansas (KS)
  • Louisiana (LA)
  • Massachusetts (MA)
  • Maine (ME)
  • Michigan (MI)
  • Minnesota (MN)
  • Missouri (MO)
  • Mississippi (MS)
  • Montana (MT)
  • North Dakota (ND)
  • Nebraska (NE)
  • New Hampshire (NH)
  • New Jersey (NJ)
  • New Mexico (NM)
  • Nevada (NV)
  • New York (NY)
  • Ohio (OH)
  • Oklahoma (OK)
  • Oregon (OR)
  • Rhode I. (RI)
  • South Dakota (SD)
  • Texas (TX)
  • Utah (UT)
  • Vermont (VT)
  • Washington (WA)
  • Wisconsin (WI)
  • 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.

Conditions in the fire evidence

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

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.

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.

Recommends (14)

Corroboration (5 rows from 5 sources)

Avoids (2)

Mid-scale / conditional (3)

Listed without a rating (18)
Corroboration (18 rows from 1 source)

  • FLAMITS: FLAMmability plant traiTS database — Dryad / Global Ecology and Biogeography · Dryad version 9 · original source Corroboration Trait database lineage: meta-aggregator

    18 cited rows from this source; its identity, lineage and tier are stated once.

    • “calorific value (kcal/kg): 2531.77”

      FLAMITS record 2886; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site Dibble2007-1; sampling ND. Primary study Dibble2007: Dibble, A. C., White, R. H., & Lebow, P. K. (2007). Combustion characteristics of north-eastern USA vegetation tested in the cone calorimeter: invasive versus non-invasive plants. International journal of wildland fire, 16, 426-443.

    • Primary study Domingos2020: Domingos, I., Ayata, U., Ferreira, J., Cruz-Lopes, L., Sen, A., Sahin, S., & Esteves, B. (2020). Calorific Power Improvement of Wood by Heat Treatment and Its Relation to Chemical Composition. Energies, 13, 5322.

      Shared row context: Combustibility measurement; plant part wood; fuel dead; predrying yes; device calorimeter; site Domingos2020-1; sampling ND.

      • “calorific value (kcal/kg): 4428.2”

        FLAMITS record 3150.

      • “calorific value (kcal/kg): 4681.38”

        FLAMITS record 3158.

      • “calorific value (kcal/kg): 4874.84”

        FLAMITS record 3166.

    • Primary study Kim1994: Kim, K., Jang, I., & Kim, S. (1994). Moisture content of litter layer and its combustibility by cigarette light in forests. Korean Journal of Ecology (Korea Republic), 17, 1-9.

      Shared row context: Ignitability measurement; plant part leaves; fuel live; predrying no; device burning bench; site Kim1994-1; sampling ND.

      • “time to flaming (s): 3.5”

        FLAMITS record 5686.

      • “time to flaming (s): 6.46”

        FLAMITS record 5694.

    • Primary study Petriccione2006: Petriccione, M. (2006). Infiammabilità della lettiera di diverse specie vegetali di ambiente mediterráneo. Tesi Di Dottorato. Università Degli Studi Di Napoli Federico II.

      Shared row context: plant part leaves; fuel live; predrying no; device epiradiator; site Petriccione2006-1; sampling may to june.

      • Shared measurement context: Ignitability measurement.

        • “time to flaming (s): 0”

          FLAMITS record 10513.

        • “ignition frequency (%): 0”

          FLAMITS record 10515.

        • “flammability value: 0”

          FLAMITS record 10516.

      • “burning duration (s): 0”

        FLAMITS record 10514; Sustainability measurement.

    • Primary study Rasooli2021: Rasooli, S. B., Rashidi, S., & Shabanian, N. (2021). Fire sensitivity of broadleaf tree species in plantations of Kurdistan, Iran. Journal of Forestry Research, 32, 1167-1176.

      Shared row context: fuel live; predrying no; device burning bench; site Rasooli2021-1.

      • “time to flaming (s): 26.93”

        FLAMITS record 10908; Ignitability measurement; plant part bark; sampling november.

      • “flaming duration (s): 23.96”

        FLAMITS record 10909; Sustainability measurement; plant part bark; sampling november.

      • “time to flaming (s): 73.47”

        FLAMITS record 10920; Ignitability measurement; plant part wood; sampling november.

      • “flaming duration (s): 114.14”

        FLAMITS record 10921; Sustainability measurement; plant part wood; sampling november.

      • “time to flaming (s): 13.23”

        FLAMITS record 10927; Ignitability measurement; plant part leaves; sampling july.

    • Primary study Shan2008: Shan, Y., Liu, N., & Shu, L. (2008). Flammability ranking of foliage species by factor analysis of physical and chemical pyric properties. Fire and Materials: An International Journal, 32, 371-382.

      Shared row context: plant part leaves; fuel live; predrying no; site Shan2008-1; sampling ND.

      • “temperature at flaming (°C): 280”

        FLAMITS record 12582; Ignitability measurement; device ignition temperature tester.

      • “calorific value (kcal/kg): 4490.2”

        FLAMITS record 12583; Combustibility measurement; device calorimeter.

    • “calorific value (kcal/kg): 5137.09”

      FLAMITS record 13718; Combustibility measurement; plant part leaves; fuel live; predrying yes; device calorimeter; site Wang2009-1; sampling november. Primary study Wang2009: Wang, X., Niu, S., & Kan, Z. (2009). Properties and flammability of major tree species in the Beijing area. Frontiers of Forestry in China, 4, 304-308.

Same genus in the directory · the Robinia group page

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

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

Robinia pseudoacacia (Purple Robe locust). FireApproved. https://fireapproved.com/plants/robinia-pseudoacacia/. Last verified 2026-08-23.