Description

• Bur oaks may be quite hefty, soaring more than 80 feet high and with a girth of better than 4 feet --- and occasionally much bigger (see Reference 1). Mature specimens are often very stout with well-furrowed bark and a broad, arcing canopy.
  
  

Habitat

• In addition to growing in eastern forest mosaics and far fringes of the western plains, bur oaks are one of the signature trees of the American prairies; in parts of the Midwest, they historically formed savannas. Indeed, ancient bur oaks in prairie states often belie their maturation in long-ago savanna settings: They have very broad crowns, recalling that now-endangered habitat's generous spacing.
  
  

Hardiness

• Bur oaks are quite hardy, tolerating cold, drought and even urban conditions (see Reference 1). Its ability to flourish in a range of soil types --- including clay-dominated sites --- does much to explain its great range (see Reference 2).
  
  

The Roots

• Bur oaks are successful in water-stressed environments partly because they develop their root systems robustly at an early age. One 8-year-old Missouri oak growing in clay soil already had 14-foot taproots sending out 11-foot laterals, according to the U.S. Forest Service (see Reference 2).
  
  

Lake Maumee Clays

• In southeastern Michigan, bur oaks are common in the clay soils associated with a former Ice Age lake, Maumee (see Reference 3).