Eucalyptus regnans, known variously as
mountain ash,
swamp gum, or
stringy gum, is a species of
Eucalyptus native to
Tasmania and
Victoria in southeastern
Australia and the tallest
flowering plant and one of the tallest trees in the world, second to the coast redwood (
Sequoia sempervirens). A straight-trunked tree with smooth grey bark and a stocking of rough brown bark to above the ground, it regularly grows to , with the tallest living specimen, the
Centurion, standing tall in
Tasmania. The white flowers appear in autumn. Victorian botanist
Ferdinand von Mueller described the species in 1871.