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Montana Field Guide

Montana Field Guides

Black Locust - Robinia pseudoacacia
Other Names:  False Acacia

Non-native Species

Global Rank: G5
State Rank: SNA

Agency Status
MNPS Threat Rank:
C-value: 1

External Links

General Description
Trees to 20 m with furrowed bark. Herbage glabrate to puberulent. Stems sometimes with nodal spines. Leaves petiolate, odd-pinnate with 9 to 17 ovate to narrowly elliptic leaflets 2–6 cm long with pubescent petiolules; stipules linear, early-deciduous. Inflorescence axillary, pendent, densely-flowered raceme 5–20 cm long. Flowers papilionaceous, white; calyx pubescent; sepals deltoid,1–3 mm long, lower 2 larger; banner 14–19 mm long with a yellow center, ca. as long as the wings and keel; stamens 9 united, 1 separate. Fruit a linear, glabrous legume flattened parallel to the sutures, 4–10 cm long, slightly indented between the seeds (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Range Comments
Collected in Lake and Missoula counties. Introduced from eastern North America to much of the U.S. and Europe (Lesica 2012. Manual of Montana Vascular Plants. BRIT Press. Fort Worth, TX).

Observations in Montana Natural Heritage Program Database
Number of Observations: 5

(Click on the following maps and charts to see full sized version) Map Help and Descriptions
Relative Density



(Observations spanning multiple months or years are excluded from time charts)


  • Additional ReferencesLegend:   View Online Publication
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    • Lesica, P., M. T. Lavin, and P. F. Stickney. 2012. Manual of Montana Vascular Plants. Fort Worth, TX: BRIT Press. viii + 771 p.
    • 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.
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Citation for data on this website:
Black Locust — Robinia pseudoacacia.  Montana Field Guide.  .  Retrieved on , from