Siberian elm was widely planted in America for windbreaks and as a disease-tolerant shade tree; it escaped cultivation and is now considered invasive in 41 states

A tree introduced to the United States for windbreaks and shade has since become a cautionary example in forestry circles. According to a 2009 study titled “Patterns of Hybridization and Introgression Between Invasive Ulmus Pumila (Ulmaceae) and Native U. Rubra,” published in the American Journal of Botany, Siberian elm has naturalized and is now considered a noxious weed/invasive species in 41 states. That's a long way from the windbreak and shade tree it was originally planted to be.