the sessile oak is a large deciduous tree up to tall, in the white oak section of the genus ("quercus" sect. "quercus") and similar to the pedunculate oak, "q. robur", with which it overlaps extensively in range. the leaves are long and broad, evenly lobed with five to six lobes on each side, and a petiole. the male flowers are called catkins, produced in the spring. the fruit is an acorn long and broad, which matures in about six months.