Eucalyptus delegatensis, commonly known as alpine ash, woollybutt, gum-topped stringybark, and white-top, is a sub-alpine or temperate tree of southeastern Australia. A straight, grey-trunked tree, it reaches heights of over 90 metres in suitable conditions. The tallest currently known specimen is located in Tasmania and is 87.9 m tall. This height is sufficient to make it the 10th tallest species of tree. Among eucalypts, only Eucalyptus regnans grows taller.
Alpine ash is a member of the Stringybark Group of eucalypts. The bark is thick, fibrous, and woolly at the base and smooth on the smaller branches. In the Tasmanian subspecies, the entire trunk and the larger limbs are thick-barked. In the mainland subspecies the rough bark extends only part-way up the trunk.
The nominate subspecies is native to cool, rocky, rugged, well-drained soils of mountainous areas between 850m and 1500 m in Victoria and New South Wales; E. d. tasmaniensis is found in most higher-altitude parts of Tasmania apart from the south-west.
Alpine ash requires very high rainfall by Australian standards — over 1,200 mm (47 in) per year and snow or frosts during the winter months. It is an important tree for the timber industry, often grouped with mountain ash and messmate stringybark and sometimes sold as "Vic Ash", "Victorian Ash", or "Tasmanian Oak".
Alpine ash often grows in naturally occurring pure stands and regenerates only from seed. While occasional fires do not severely impact alpine ash forest, repeated fires in the same area can destroy stands because it takes roughly twenty years for seedlings to reach sexual maturity.