How do you lichen me now?
GO for a walk along a country lane or city high street—it matters not which—and you will see lichen. From below the high tide of a rocky shore to the tops of high mountains, from just south of the North Pole to just north of the South Pole, lichens are quietly living their lives. Lichens are the most widespread of all complex organisms and yet we pass them by, unnoticed and disregarded, also-rans after the furry, the feathery and the flowery. Yet beautiful they certainly are, with sometimes brilliant colours, and exquisite in both their sculptural detail and functional complexity.
Lichen biology is a mystery to most, but the fundamental facts are simple enough. A lichen is a symbiosis, a mutualism, between a fungus (the structural part) and a ‘photobiont’, which will be either (rarely both) an alga or a cyanobacterium. The photobionts supply both themselves and their fungal partner with the carbohydrates of photosynthesis. When the relationship
