
Bur oak drops the largest acorns of any North American oak — up to two inches across with a shaggy fringed cap — and they land hard enough to dent a car hood and are a real rolling-ankle hazard on a walk or drive. Mast years are irregular, arriving every few years, and the tree also sheds thick leathery leaves that resist mowing and mulch slowly.
Seventy to eighty feet tall and about as wide, growing slowly to moderately, with typical lifespans of 200-300 years and good specimens well past 400. Cost is at the very top of the bracket: huge spread, extremely dense heavy wood, and the trunk diameters these reach usually make removal a crane job, which is the strongest practical argument for preserving one rather than taking it.