Nation The oldest known tree in Wisconsin is a 1,300-year-old cedar growing from a cliff April 23, 2019Robert Mentzer, Wausau Daily HeraldComments Off on The oldest known tree in Wisconsin is a 1,300-year-old cedar growing from a cliff The oldest tree in Wisconsin is not a towering pine or a massive oak. It's a scrub of a tree growing unnoticed from the side of a cliff.