Robinia pseudoacacia Linnaeus
Paul Wray, Iowa State University
Forestry and Natural Areas
Black locust poses a serious threat to native vegetation in dry and sand prairies, oak savannas and upland forest edges, outside of its historic North American range. Native North American prairie and savanna ecosystems have been greatly reduced in size and are now represented by endangered ecosystem fragments. Once introduced to an area, black locust expands readily into areas where their shade reduces competition from other (sun-loving) plants. Dense clones of locust create shaded islands with little ground vegetation. Lack of ground fuel limits the use of fire in natural disturbance regimes. The large, fragrant blossoms of black locust compete with native plants for pollinating bees. <www.invasive.org>
In 100 Years of Change in the Distribution of Common Indiana Weeds by William and Edith Overlease (2002) reported that black locust was found in Indiana in 1899 (Coulter’s Catalogue of Indiana Plants). Black locust was “common throughout the state through planting and naturalization. The dense, hard wood is of great value and from an economic standpoint has few superiors. Locally it was principally used for posts and wagon wheels”. It was reported in Clark, Daviess, Decatur, Delaware, Franklin, Gibson, Jay, Jefferson, Monroe, Posey, Putnam, Randolph, Shelby, Vigo, and Wayne counties.
Black locust was reported in 1940 (Deam’s Flora) in Bartholomew, Daviess, Dearborn, Decatur, Franklin, Hamilton, Hancock, Henry, Jasper, Jefferson, Johnson, LaGrange, La Porte, Lawrence, Marion, Morgan, Monroe, Montgomery, Newton, Noble, Perry, Parke, Porter, Posey, Putnam, Ripley, St. Joseph, Steuben, Tippecanoe, and Wells counties. Deam noted that “this species has been freely planted since pioneer times and has escaped in all parts of the state. It was no doubt, a native in the southeastern part of the state near the Ohio River.
In 2002 (Overlease) observed that black locust had escaped and spread from plantings. It can be found in following 65 counties in Indiana: Adams, Bartholomew, Blackford, Brown, Carroll, Cass, Clark, Clay, Clinton, Crawford, Dearborn, Decatur, Dubois, Elkhart, Fayette, Fountain, Fulton, Gibson, Grant, Hamilton, Hancock, Henry, Jay, Jefferson, Knox, Kosciusko, LaGrange, Lake, Lawrence, Madison, Marion, Marshall, Martin, Miami, Monroe, Morgan, Noble, Ohio, Orange, Owen, Parke, Perry, Pike, Porter, Posey, Putnam, Randolph, Ripley, Rush, St. Joseph, Shelby, Spencer, Steuben, Sullivan, Switzerland, Tippecanoe, Tipton, Union, Vermillion, Vigo, Warren, Warrick, Washington, Wayne, and White.