Robinia pseudoacacia - L.
Black Locust
Other Common Names: black locust
Taxonomic Status: Accepted
Related ITIS Name(s): Robinia pseudo-acacia Linnaeus (TSN 26185) ;Robinia pseudoacacia L. (TSN 504804)
Unique Identifier: ELEMENT_GLOBAL.2.157931
Element Code: PDFAB3G080
Informal Taxonomy: Plants, Vascular - Flowering Plants - Pea Family
Kingdom Phylum Class Order Family Genus
Plantae Anthophyta Dicotyledoneae Fabales Fabaceae Robinia
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Concept Reference
Concept Reference: Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.
Concept Reference Code: B94KAR01HQUS
Name Used in Concept Reference: Robinia pseudoacacia
Conservation Status

NatureServe Status

Global Status: G5
Global Status Last Reviewed: 11Oct1983
Global Status Last Changed: 11Oct1983
Rounded Global Status: G5 - Secure
Nation: United States
National Status: N5
Nation: Canada
National Status: NNA (17Oct2016)

U.S. & Canada State/Province Status
Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
United States Alabama (SNR), Arkansas (SNR), California (SNR), Colorado (SNR), Connecticut (SNA), Delaware (SNA), District of Columbia (SNR), Florida (SNR), Georgia (SNR), Idaho (SNR), Illinois (SNR), Indiana (SNR), Iowa (SNA), Kansas (SNR), Kentucky (S5), Louisiana (SNR), Maine (SNA), Maryland (SNR), Massachusetts (SNR), Michigan (SNA), Minnesota (SNA), Mississippi (SNR), Missouri (SNR), Montana (SNA), Nebraska (SNR), Nevada (SNR), New Hampshire (SNR), New Jersey (SNA), New Mexico (SNA), New York (SNA), North Carolina (S5), North Dakota (SNR), Ohio (SNR), Oklahoma (SNR), Oregon (SNR), Pennsylvania (S5), Rhode Island (SNA), South Carolina (SNR), South Dakota (SNA), Tennessee (SNR), Texas (SNR), Utah (SNR), Vermont (SNR), Virginia (S5), Washington (SNR), West Virginia (S5), Wisconsin (SNR), Wyoming (SNA)
Canada British Columbia (SNA), New Brunswick (SNA), Nova Scotia (SNA), Ontario (SNA), Prince Edward Island (SNA), Quebec (SNA)

Other Statuses

NatureServe Global Conservation Status Factors

Other NatureServe Conservation Status Information

U.S. States and Canadian Provinces

Due to latency between updates made in state, provincial or other NatureServe Network databases and when they appear on NatureServe Explorer, for state or provincial information you may wish to contact the data steward in your jurisdiction to obtain the most current data. Please refer to our Distribution Data Sources to find contact information for your jurisdiction.
Color legend for Distribution Map
NOTE: The distribution shown may be incomplete, particularly for some rapidly spreading exotic species.

U.S. & Canada State/Province Distribution
United States AL, AR, CA, CO, CTexotic, DC, DEexotic, FL, GA, IAexotic, ID, IL, IN, KS, KY, LA, MA, MD, MEexotic, MIexotic, MNexotic, MO, MS, MTexotic, NC, ND, NE, NH, NJexotic, NMexotic, NV, NYexotic, OH, OK, OR, PA, RIexotic, SC, SDexotic, TN, TX, UT, VA, VT, WA, WI, WV, WYexotic
Canada BCexotic, NBexotic, NSexotic, ONexotic, PEexotic, QCexotic

Range Map
No map available.

Ecology & Life History Not yet assessed
Economic Attributes Not yet assessed
Management Summary Not yet assessed
Population/Occurrence Delineation Not yet assessed
Population/Occurrence Viability
U.S. Invasive Species Impact Rank (I-Rank)
Disclaimer: While I-Rank information is available over NatureServe Explorer, NatureServe is not actively developing or maintaining these data. Species with I-RANKs do not represent a random sample of species exotic in the United States; available assessments may be biased toward those species with higher-than-average impact.

I-Rank: High/Medium
Rounded I-Rank: High
I-Rank Reasons Summary: This is often a species of low-quality disturbed sites but it also invades some important, high-quality prairie and savanna ecosystems where it can significantly alter community structure and species composition. In addition, its ability to fix nitrogen may have significant impacts on some ecosystems, including facilitating invasion by other non-native species. The legacy of these impacts may persist, even long after the locust trees have been removed. Removal is considered difficult, with monitoring and re-treatment over several years necessary.
Subrank I - Ecological Impact: High/Medium
Subrank II - Current Distribution/Abundance: High
Subrank III - Trend in Distribution/Abundance: Medium/Low
Subrank IV - Management Difficulty: Medium
I-Rank Review Date: 22Mar2006
Evaluator: K. Maybury
Native anywhere in the U.S?
Native Range: Although the exact native range cannot be determined (Isley 1998), most sources consider this species native to the central and southern Appalachians and the Ozarks.

Download "An Invasive Species Assessment Protocol: Evaluating Non-Native Plants for their Impact on Biodiversity". (PDF, 1.03MB)
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Screening Questions

S-1. Established outside cultivation as a non-native? YES
Comments: Widely established in the U.S. outside its native range.

S-2. Present in conservation areas or other native species habitat? Yes

Subrank I - Ecological Impact: High/Medium

1. Impact on Ecosystem Processes and System-wide Parameters:High significance
Comments: This is a nitrogen-fixing species that may have long-persisting effects on some ecosystems. In Massachusetts, in a nutrient-limited and generally invasion-resistant landscape, this species has been found to facilitate invasion by other non-native plants, probably through increasing soil nitrogen (Von Holle et al. 2005). Further, elevated soil nitrogen, especially ammonium, has been found to continue for many years after the locust trees are removed (Von Holle 2005). These former locust stands (now generally with native black cherry in the overstory) continue to have higher non-native species richness than native pine-oak stands in the same area (Von Holle 2005). Where black locust has shaded out (eliminated) the ground layer vegetation, fire regimes may also be altered (Wieseler 2005).

2. Impact on Ecological Community Structure:High significance
Comments: This species can form dense stands of trees in areas that were formerly prairie or savanna (Converse 1984). Dense stands of locust can create shaded 'islands' with little ground vegetation (Wieseler 2005).

3. Impact on Ecological Community Composition:Moderate significance
Comments: The dense clonal stands that this species forms can be harmful to native plants as they shade out most understory vegetation (Wisconsin DNR 2004, Wieseler 2005); forms single-species stands (Minnesota DNR 2006). May also significantly influence the insect community: fewer arthropod speices were found on Robinia pseudoacacia than on a native locust, Robinia neomexicana, in a 2-year study in Arizona, and only 12 species (out of 251 found on the native) were also found on Robinia pseudoacacia (Degomez and Wagner 2001).

4. Impact on Individual Native Plant or Animal Species:Low significance/Insignificant
Comments: The fragrant blossoms may compete with native plants for pollinating bees (Wieseler 2005).

5. Conservation Significance of the Communities and Native Species Threatened:Medium/Low significance
Comments: Although this species is very commonly associated with low-quality disturbed habitats (degraded woodlots, roadsides, etc.), it poses a serious threat to high quality prairie and oak savanna ecosystems in the Midwest (Converse 1984, Wieseler 2005). These systems have been dramatically reduced in size and the remaining fragments are endangered (Wieseler 2005). It was also one of several species listed as a severe threat to a unique and very high quality native floodplain woodland in California (Meyers-Rice 2001). Wieseler (2005) notes: "black locust clones easily spread in [good] quality and restorable natural areas."

Subrank II. Current Distribution and Abundance: High

6. Current Range Size in Nation:High significance
Comments: Established widely outside of its native range per Kartesz (1999).

7. Proportion of Current Range Where the Species is Negatively Impacting Biodiversity:Moderate significance
Comments: Uncommon in parts of the West, especially the Great Plains (Isely 1998, Kartesz 2006 draft county distribution data) and perhaps not problematic there, but with some negative impacts assumed in most of the non-native range.

8. Proportion of Nation's Biogeographic Units Invaded:High significance

9. Diversity of Habitats or Ecological Systems Invaded in Nation:Moderate significance
Comments: Dry, upland prairies, sand prairies, oak savannas (Converse 1984, Wisconsin DNR 2004, Minnesota DNR 2006), as well as disturbed areas such as degraded woods/woodlots, woodland margins pastures, old fields, roadsides, urban areas (Isely 1998, Wisconsin DNR 2004, Minnesota DNR 2006).

Subrank III. Trend in Distribution and Abundance: Medium/Low

10. Current Trend in Total Range within Nation:Low significance
Comments: Inferred; already widespread in terms of generalized range.

11. Proportion of Potential Range Currently Occupied:Insignificant
Comments: Inferred.

12. Long-distance Dispersal Potential within Nation:Moderate significance
Comments: Formerly sold and planted extensively and still used for erosion control, mine reclamation, etc.

13. Local Range Expansion or Change in Abundance:Medium significance/Insignificant
Comments: Unknown, but there is no reason to think that extreme increases are occurring. Significant declines in landcover over the last 30 years were documented on Cape Cod (Von Holle 2005) but many areas are probably experiencing increases simply due to increased human disturbance.

14. Inherent Ability to Invade Conservation Areas and Other Native Species Habitats:Medium/Low significance
Comments: This is an early successional species (Wieseler 2005). It does not grow well in competition with other plants (trees, vines, or grasses) and some plantings have failed in grassy areas because of competing grasses (Converse 1984). However, this species can invade undisturbed sand prairies (Anderson and Brown 1980 as cited in Converse 1984; R. Henderson, pers. comm. to C. Converse 1984), which are somewhat dry and open. It may be able to invade these dry prairies and savannas as its extensive root system allows it to tolerate dry sites and it grows vigorously in full sun where herbaceous vegetation is sparse (Converse 1984).

15. Similar Habitats Invaded Elsewhere:Low significance
Comments: This is a problematic plant in woodlands in many countries (Sabo 2000). It has naturalized in disturbed lands, grasslands, and woodlands in Europe (Sabo 2000; Weeds Australia, not dated) and in Australia (Weeds Australia, not dated).

16. Reproductive Characteristics:Moderate significance
Comments: Stongly exhibits two characteristics typical of invasive plant species:
1. Vegetative reproduction via root suckering and stump sprouting is vigorous (Wisconsin DNR 2004, Minnesota DNR 2006).
2. Early height growth exceeds that of most other trees, and can average as much as 4 feet per year on good sites (Converse 1984). (Although this species produces copius seeds these do not readily germinate without disturbance that penetrates the thick seed coat [Wisconsin DNR 2004] so the high seed production was not considered.)

Subrank IV. General Management Difficulty: Medium

17. General Management Difficulty:Moderate significance
Comments: This species is generally considered fairly difficult to manage once established. Chemical, rather than mechanical, controls are needed (see Wisconsin DNR 2004).

18. Minimum Time Commitment:Moderate significance
Comments: Plants apparently killed by herbicide can resprout several years after treatment (R. Henderson, pers. comm. to C. Converse, 1984, Wieseler 2005).

19. Impacts of Management on Native Species:Low significance
Comments: Foliar spray can be used on small, low patches of trees (Wisconsin DNR 2004) but there is the potential for non-target damage. Even basal stem application of herbicide to individual trees can be somewhat harmful as the chemicals need to be disolved in substances that release volatile organic compounds into the atmosphere (Wisconsin DNR 2004).

20. Accessibility of Invaded Areas:Moderate significance
Comments: There are many plantings on private lands.

Botanical data developed by NatureServe and its network of natural heritage programs (see Local Programs), The North Carolina Botanical Garden, and other contributors and cooperators (see Sources).

  • Converse, C. K. 1994. Element Stewardship Abstract for Black locust (ROBINIA PSEUDOACACIA). The Nature Conservancy, unpublished report. 14 p. Online at:

  • Deam, C. C. 1940. Flora of Indiana. Division of Forestry, Dept. of Conservation, Indianapolis, Indiana. 1236 pp.

  • Degomez, R. and M. R. Wagner. 2001. Arthropod diversity of exotic vs. native Robinia species in northern Arizona. Agricultural and Forest Entomology 3(1): 19-27.

  • Douglas, G.W., D. Meidinger, and J. Pojar. eds. 1999. Illustrated Flora of British Columbia, Vol. 3, Dicotyledons (Diapensiaceae through Onagraceae). B.C. Minist. Environ., Lands and Parks, and B.C. Minist. For., Victoria. 423pp.

  • Isely, D. 1998. Native and naturalized Leguminosae (Fabaceae) of the United States (exclusive of Alaska and Hawaii). Monte L. Bean Life Science Museum, Brigham Young University; MLBM Press, Provo, Utah. 1007 pp.

  • Kartesz, J.T. 1994. A synonymized checklist of the vascular flora of the United States, Canada, and Greenland. 2nd edition. 2 vols. Timber Press, Portland, OR.

  • Kartesz, J.T. 1996. Species distribution data at state and province level for vascular plant taxa of the United States, Canada, and Greenland (accepted records), from unpublished data files at the North Carolina Botanical Garden, December, 1996.

  • Kartesz, J.T. 1999. A synonymized checklist and atlas with biological attributes for the vascular flora of the United States, Canada, and Greenland. First edition. In: Kartesz, J.T., and C.A. Meacham. Synthesis of the North American Flora, Version 1.0. North Carolina Botanical Garden, Chapel Hill, N.C.

  • Little, E.L., Jr. 1979. Checklist of United States trees (native and naturalized). Agriculture Handbook No. 541. U.S. Forest Service, Washington, D.C. 375 pp.

  • Meyers-Rice, B. 2001. A success story: Cosumnes River Preserve, central California. The Nature Conservancy, Wildland Invasive Species Program. Available at:

  • Minnesota Department of Natural Resources [DNR]. 2006. Black locust (Robinia pseudoacacia). Online: Accessed 2006.

  • Morton, J.K., and J.M. Venn. 1990. A checklist of the flora of Ontario vascular plants. University of Waterloo, Waterloo, Canada. 218 pp.

  • Sabo, A. 2000. Robinia pseudoacacia: A tree of controversy. Restoration and Reclamation Review, Volume 6.3: Invasive nitrogen fixers. Online: Accessed 2006.

  • Swink, F., and G. Wilhelm. 1994. Plants of the Chicago Region. Morton Arboretum. Lisle, Illinois.

  • USDA, ARS, National Genetic Resources Program. 2005. December 9 last update. Germplasm Resources Information Network (GRIN) Online Database. National Germplasm Resources Laboratory, Beltsville, Maryland. Available: http://www.ars-grin.gov2/cgi-bin/npgs/html/ (Accessed 2006).

  • Von Holle, B. 2005. Ecosystem effects and legacies of the introduced N-fixing tree, Robinia pseudoacacia, in the upland coastal forests of Cape Cod, MA. Harvard Forest Symposium Abstracts, Harvard University.

  • Von Holle, B., K. A. Joseph, E. F. Largay, and R. G. Lohnes. 2005. Facilitations between the introduced nitrogen-fixing tree, Robinia pseudoacacia, and nonnative plant species in the glacial outwash upland ecosystem of Cape Cod, MA. Biodiversity and Conservation (Issue: Online First, an online publication). SpringerLink electronic data source.

  • Weeds Australia, an Australian Weeds Committee national initiative. Not dated. Black locust. Online: Accessed 2006.

  • Wieseler, S. 2005. Black locust: Robinia pesudoacacia L. Plant Conservation Alliance Alien Plant Working Group. Online: Accessed 2006.

  • Wisconsin Department of Natural Resources [DNR]. 2004. Black locust (Robinia pseudoacacia). Online: Accessed 2006.

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