Eucalyptus pyrenea is a slender tree that typically grows to a height of and forms a
lignotuber. It has smooth, greyish bark with some rough, fibrous or flaky bark near the base. Young plants and
coppice regrowth have dull, bluish green leaves that are slightly paler on the lower surface, egg-shaped to elliptical, long and wide. Adult leaves are the same shade of shiny green on both sides, lance-shaped to curved, long and wide on a
petiole long. The flower buds are arranged in leaf
axils in groups of seven on a thin, flattened, unbranched
peduncle long, the individual buds on
pedicels long. Mature buds are oval to cylindrical, long and wide with a conical
operculum about the same length and width as the
floral cup. Flowering occurs in autumn and the flowers are white. The fruit is a woody, cup-shaped
capsule long and wide with the valves below rim level. ==Taxonomy==