WordNet sense 1 (a common scrubby deciduous tree of central and southeastern United States having dark bark and broad three-lobed (club-shaped) leaves; tends to form dense thickets):

blackjack, blackjack oak, Quercus marilandica

WordNet sense 2 (small to medium deciduous oak of east central North America; leaves have sharply pointed lobes):

northern pin oak, Quercus ellipsoidalis