Robinia pseudoacacia, commonly known in its native territory as black locust, is a medium-sized deciduous tree native to the southeastern United States, but it has been widely planted and naturalized elsewhere in temperate North America. Black locust reaches a typical height of 40–100 feet (12–30 m) with a diameter of 2–4 feet (0.61–1.22 m). Exceptionally, it may grow up to 52 metres (171 ft) tall and 1.6 metres (5.2 ft) diameter in very old trees. It is a very upright tree with a straight trunk and narrow crown which grows scraggly with age. The dark blue-green compound leaves with a contrasting lighter underside give this tree a beautiful appearance in the wind and contribute to its grace.