Quercus tardifolia, the Chisos Mountains oak or lateleaf oak, is a rare North American species of trees in the beech family. It has been found in the Chisos Mountains inside Big Bend National Park in Texas, and in the nearby Sierra del Carmen across the Río Grande in northern Coahuila. Quercus tardifolia is an evergreen tree with gray bark and reddish-brown twigs. Leaves are flat, up to 10 cm (4 inches) long, green on the upper surface but woolly hairs on the underside, with a few shallow lobes.