Most of the oaks are deciduous trees, but there are some evergreen species such as Holm oak (Quercus ilex).

Male and female flowers are on the same plant, but are separated. The fruit of the oak tree is acorn. Some species such as the sessile oak (Quercus petraea) and the English oak (Quercus robur) can grow up to 40 m in height, while some species such as the downy oak (Quercus pubescens) grow to 15 meters in height.
In addition to being used in the manufacture of furniture, carpentry, and items made of wood, oak wood is the main material for producing the highest quality wood flooring and wall coverings.