Eucalyptus comitae-vallis is a mallee, rarely a tree, that typically grows to a height of and forms a
lignotuber. The bark is rough, ribbony and grey on the trunks and larger branches then smooth and pinkish grey yellow-green above. Leaves on young plants and
coppice regrowth are dull, greyish, long and wide and always have a
petiole. Adult leaves are linear to narrow lance-shaped, the same more or less glossy green on both sides, long and wide on a petiole long. The flower buds are arranged in groups of seven, nine or eleven in leaf
axils on a
peduncle long, the individual buds on a
pedicel long. Mature buds are cylindrical to narrow pear-shaped, long and wide with a rounded to flattened
operculum with a short beak. Flowering occurs from February to April and the flowers are white. The fruit is a woody, barrel-shaped to conical or cup-shaped
capsule long and wide on a pedicel long and with the valves at rim level. ==Taxonomy==