A quantitative cluster analysis of lichen distribution data demonstrates that the main biogeographical subdivision in the world's lichen biota is into a Gondwanan and a Laurasian element. Patterns at smaller scales mainly reflect local climate. Wallace's line is not a significant boundary for lichens. The Gondwana / Laurasia split also applies to lichenicolous fungi. To a considerable extent, it applies to many of the larger families and orders of lichens too, though at these ranks the affinities of the lichen biota of eastern Asia and temperate North America are sometimes ambiguous.
