On warm days eucalyptus oil vapour rises above the bush to create the well-known distant blue haze of the Australian landscape. Eucalyptus oil catches fire very easily, and bush fires can travel quickly through the oil-rich air of the tree crowns. The dead bark and fallen branches are also flammable. Eucalypts are well adapted for periodic fires – in fact most species are dependent on them for spread and regeneration. They do this in several ways: by sprouting from underground tubers, hidden buds under their bark and from seeds sprouting in the ashes after the fire has opened them.