A long-lived, deciduous tree to 30-80βH a trunk 1-4.5β in diameter. In open areas the crown is broad and rounded, with lower branches nearly touching the ground or forming a browse line. Dark bark, which gives it its name, is thin and smooth in young trees, becoming moderately thick, deeply fissured and platy with age. 1-1-1/2β acorns, considered the best acorns for food by the Native Americans, take two years to mature. 4-8β long, deeply lobed leaves are often spiny on the tips of the lobes.