Eucalyptus forrestiana is a small tree or mallet that typically grows to a height of and does not form a
lignotuber. It has smooth grey over pale brown bark and a dense dark green canopy. Young plants and
coppice regrowth have dull greyish green,
petiolate leaves that are arranged alternately, egg-shaped to lance-shaped, long and wide. Adult leaves are also arranged alternately, lance-shaped, the same glossy green on both sides when mature, long and wide. The flowers buds are arranged singly in leaf axils on a flattened
peduncle long, the
pedicel long. Mature buds are red, oblong in side view, square in cross-section, long and wide with a narrow wing on each corner and a flat, disc-like
operculum. Flowering occurs from January to March or from April to June and the flowers are yellow. The fruit is a similar shape to the flower buds, long and wide with the valves enclosed below the level of the rim. ==Taxonomy==