The Wisconsin weeping willow is a hardy, graceful tree that, surprisingly, is not native to Wisconsin. Anyone who has ever given its long, drooping branches a "haircut" knows that it needs periodic maintenance to stay strong but is otherwise culturally undemanding. Like most willows, Wisconsin weeping willow flourishes near water and adapts well to rivers and wetlands--even in Wisconsin.
Wisconsin weeping willow is a deciduous tree that grows to a height of 30 feet or more. It has a wide crown and shallow roots and slender leaves up to 6 inches long that hang from trailing branches. The U.S. Department of Agriculture (USDA) classifies Wisconsin weeping willow as salix pendulina, a non-native species that is perhaps a cross between s. fragilis and s. sepulcralis. The Ohio State University identifies it as salix x blanda, a cross between s. babylonica and s. fragilis.
Wisconsin weeping willow's possible ancestors are European; S. fragilis (Brittle or Crack Willow) is named for its branches, which break easily. S. babylonica has a relatively shorter trunk but is less hardy than the Wisconsin weeping willow. Wisconsin weeping willow's origins are unknown but the U.S. Department of Agriculture lists it as non-native in North America.
The tree has adapted well; its range is the West Coast from Washington down to California, interior states from Texas through Missouri, Illinois, Indiana, Michigan; and the East Coast, from Maine down to Georgia. It also grows in the Canadian provinces of British Columbia and Ontario.
Willows prefer moist to wet soils. They grow in wetlands throughout most of their range except in the Northwest where they grow equally well in wetland and non-wetland areas. Willows grow in full sun to part shade and are hardy from USDA zone 2 to 9A, excluding only south Florida from its potential range. It is undemanding as to pH and has good salt tolerance in both soil and air. Willows often spread as wide as they grow tall; a willow tree will require plenty of space.
Wisconsin willows are large trees. Their favorite habitats are wetlands and riverbanks. They also thrive on large lawns and golf courses. Their success in urban areas, small residential lots or near septic tanks would be doubtful; they are messy, not reliably tolerant of pollutants and their strong roots have been known to lift sidewalks.
Yulia A. Kuzovkina and Martin F. Quigley, in their paper "Willows Beyond Wetlands: Uses of Salix L. Species for Environmental Projects", argue that willow's adaptability and undemanding requirements for fertilization make it a good choice for restoring damaged ecosystems and control ling erosion.
Wisconsin weeping willows are hardy willows that make good candidates for ecological restoration and engineering. Their use in residential settings may be limited by the tendency of their roots to grow at the surface, choking out other vegetation like turf grass. They are, however, great candidates for wetland areas, swales and low, wet areas where grass will not grow well anyway.