black locust USDA PLANTS Symbol: ROPS
U.S. Nativity: Native
Habit: Hardwood Trees
Robinia pseudoacacia L.

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Taxonomic Rank: Magnoliopsida: Fabales: Fabaceae (Leguminosae)
Synonym(s): false acacia, yellow locust
Native Range: U.S.- East: southern and central Appalachians from northern GA to PA and Ozarks- AR, MO and OK, ()

Black locust is a deciduous tree that, while native to parts of the United States, has spread to and become invasive in other parts of the country. Trees grow from 40-100 ft. (12-30 m) in height. Trees grow upright in forests, but develop an open growth form in more open areas. Leaves are pinnately compound with 7-21 small, round leaflets per leaf. Leaflets are 1.5 in. (4 cm) long. A pair of long, stipular spines is found at the base of most leaves. Flowering occurs in the spring, when flowers develop in 8 in. (20.3 cm) long clusters. The showy, fragrant, white to yellow flowers give way to a smooth, thin seed pod that is 2 to 4 in. (5.1-10.2 cm) in length. The bark of black locust is light brown, rough, and becomes very furrowed with age. Black locust is native to the Southern Appalachians, the Ozarks, and other portions of the Midsouth, but is considered an invasive species in the prairie and savanna regions of the Midwest where it can dominate and shade those open habitats.

Identification, Biology, Control and Management Resources

Selected Images from Invasive.orgView All Images at Invasive.org


Diagram or Graphic; 1. Branchlet with flowering and leafy shoots. Pea-flower shaped (»papilionaceous«) flowers open in pendulous terminal racemes. Odd-pinnate compound leaves with short petioluled leaflets. - 2. Shoot with ripe pods (f) and pendulous leaflets (B) during night. Fruits are many-seeded flat pods. - 3. Ripe seed as seen from two aspects. - 4. Seedling with cotyledons (c) and first ordinary leaves. - 5. Winter-branchlet - terminal bud is missing. Buds are small, naked, hidden inside the leaf scars and typically located between two modified spiny stipules. After Hempel & Wilhelm, 1889. Photos and explanations from the book: Zelimir Borzan. "Tree and Shrub Names in Latin, Croatian, English, and German, with synonyms", University of Zagreb, 2001.
Zelimir Borzan, University of Zagreb, Bugwood.org
Additional Resolutions & Image Usage

Foliage;
Jan Samanek, State Phytosanitary Administration, Bugwood.org
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Foliage;
Paul Wray, Iowa State University, Bugwood.org
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Foliage;
James H. Miller, USDA Forest Service, Bugwood.org
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Foliage;
James H. Miller, USDA Forest Service, Bugwood.org
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Bark;
Paul Wray, Iowa State University, Bugwood.org
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Feature(s); Stipular Spines
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Flower(s);
Paul Wray, Iowa State University, Bugwood.org
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Flower(s);
Jan Samanek, State Phytosanitary Administration, Bugwood.org
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Flower(s);
Jan Samanek, State Phytosanitary Administration, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Bill Cook, Michigan State University, Bugwood.org
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Flower(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Jan Samanek, State Phytosanitary Administration, Bugwood.org
Additional Resolutions & Image Usage

Flower(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Fruit(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s);
Jan Samanek, State Phytosanitary Administration, Bugwood.org
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Fruit(s); fruits remaining in spring from previous year
Jan Samanek, State Phytosanitary Administration, Bugwood.org
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Fruit(s);
Paul Wray, Iowa State University, Bugwood.org
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Fruit(s); fruit and seeds
Richard Old, XID Services, Inc., Bugwood.org
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Fruit(s);
Jan Samanek, State Phytosanitary Administration, Bugwood.org
Additional Resolutions & Image Usage

Fruit(s); fruit and seeds
Paul Wray, Iowa State University, Bugwood.org
Additional Resolutions & Image Usage

Feature(s); Clonal Growth
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Tree(s);
Leslie J. Mehrhoff, University of Connecticut, Bugwood.org
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Tree(s); in flower
Jan Samanek, State Phytosanitary Administration, Bugwood.org
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Tree(s);
Chris Evans, River to River CWMA, Bugwood.org
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Seedling(s);
Brian Lockhart, USDA Forest Service, Bugwood.org
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Sapling(s); Yound sapling growing within a 50 year old pine stand. Poland
Gil Wojciech, Polish Forest Research Institute, Bugwood.org
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Seed(s);
Steve Hurst, USDA NRCS PLANTS Database, Bugwood.org
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Diagram or Graphic; Britton, N.L., and A. Brown. 1913. Illustrated flora of the northern states and Canada. Vol. 2: 375.
USDA PLANTS Database, USDA NRCS PLANTS Database, Bugwood.org
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EDDMapS Distribution:
This map is incomplete and is based only on current site and county level reports made by experts and records obtained from USDA Plants Database. For more information, visit www.eddmaps.org
 


State(s) Where Reported invasive.
Based on state level agency and organization lists of invasive plants from WeedUS database.

U.S. National Parks where reported invasive:
Death Valley National Park (California)
Indiana Dunes National Lakeshore (Indiana)
Yosemite National Park (California)



Invasive Listing Sources:
California Invasive Plant Council
City of Ann Arbor Michigan Parks and Recreation
Connecticut Invasive Plant Working Group
Indiana Native Plant and Wildflower Society
Invasive Plant Council of New York State
Jil M. Swearingen, Survey of invasive plants occurring on National Park Service lands, 2000-2007
John Randall, The Nature Conservancy, Survey of TNC Preserves, 1995.
Mid-Atlantic Exotic Pest Plant Council, 2005
Minnesota Department of Natural Resources, 1998
Missouri Department of Conservation,
National  Wildlife Refuge Association, Silent Invasion: A Call to Action from the National Wildlife Refuge Association, 2002. Washington DC. 17 pp.
Native Plant Society of Oregon, 2002
New Jersey Department of Agriculture, Division of Plant Industry, 2004
Pacific Northwest Exotic Pest Plant Council, 1998
Pennypack Ecological Restoration Trust, Pennsylvania.
Reichard, Sarah. 1994.  Assessing the potential of invasiveness in woody plants introduced in North America. University of Washington Ph.D. dissertation.