Quercus palustris is an oak in the red oak section. Pin oak is one of the most commonly used landscaping oaks in its native range due to its ease of transplant, relatively fast growth, and pollution tolerance. Its distinctive shape is considered unique among hardwoods.
Pin oak is a medium-sized deciduous tree growing to 18–22m tall, with a trunk up to 1m diameter. It has an 8–14m spread. Young trees have a straight, columnar trunk with smooth bark and a pyramidal canopy. By the time the tree is 40 years old, it develops more rough bark with a loose, spreading canopy.
This canopy is considered one of the most distinctive features of the pin oak: the upper branches point upwards, the middle branches are at right angles to the trunk, and the lower branches droop downwards.
The leaves are broad with five or seven lobes. Each lobe has five to seven bristle-tipped teeth. The flowers are monoecious catkins which, being self-incompatible, require the presence of another oak for pollination. Any species in the red oak group can serve as a pollinator, but in pin oak's natural range, this will usually be northern red oak or scarlet oak. Interspecies hybridization occurs freely. The acorns require two growing seasons to develop.