Until seven years ago, there was a standard answer to this question: the President’s Oak, a bur oak that stood on Observatory Hill, was broadly believed to be the UW’s oldest tree. There are about 4,000 trees on campus, and though some are thicker (such as cottonwoods and elms, which grow fast) and some are taller, none was thought to be as old as the President’s Oak, which had probably passed its 300th birthday. Sadly, it began rotting from the inside, and it was cut down in January 2015. We say “broadly believed,” however, because the only certain way to tell a tree’s age is by cutting into its core and counting its rings, and by the time the President’s Oak came down, its trunk was about three-quarters hollow. Without rings, horticulturists have to estimate a tree’s age based on species and growing conditions. With that in mind, Daniel Einstein MS’95, the UW’s longtime historic and cultural resources manager, says the oldest tree now is likely another bur oak, located between two effigy mounds about 75 yards west of where the President’s Oak stood. It, too, is about 300 years old. Probably.