Which tree species is the tallest flowering plant, native to Tasmania and Victoria?

The tallest flowering plant, native to Tasmania and Victoria, is Eucalyptus regnans.

Known as mountain ash in Victoria and giant ash or swamp gum in Tasmania, Eucalyptus regnans is a towering evergreen eucalypt of wet, high-rainfall forests. Its smooth pale trunk usually has a rough, fibrous bark stocking at the base, and its white flowers appear in groups of nine to fifteen.

The species is recognized as the tallest of all flowering plants. Centurion, a living Tasmanian specimen, measures about 100.5 metres. Historical claims are even higher, including the 132.6-metre Ferguson Tree, but that old measurement remains disputed. This distinction concerns flowering plants, so it is not the same as claiming the species is definitively the tallest plant of any kind.

Eucalyptus regnans lacks a lignotuber, a woody underground swelling that can help some eucalypts resprout after fire. Severe bushfires may therefore kill mature trees, but the species regenerates from seeds released after disturbance. Its timber is sold with Eucalyptus obliqua and Eucalyptus delegatensis as Tasmanian oak.