Eucalyptus rigens is a sprawling, sometimes almost prostrate mallee that typically grows to a height of . It has smooth grey over white bark that peels in strips. Young plants and
coppice regrowth have leaves that are up to long and wide. Adult leaves are the same shade of greyish to light green on both sides, lance-shaped, up to long and wide, firm, stiff and often erect. The flower buds are arranged in leaf
axils in groups of three on a strongly flattened peduncle up to long. Mature buds are oval, ribbed, up to long and wide with a ribbed, conical
operculum. Flowering occurs from July to September and the flowers are creamy white. The fruit is a woody, sessile, cup-shaped or conical
capsule long and wide with the valves near rim level. ==Taxonomy and naming==