The Revised Second Edition of Flora of New Zealand: Lichens is an updated and definitive guide to the country's rich and diverse lichen flora. This revised identification manual comprises two volumes and supersedes the version published in 1985 and includes for the first time a treatment of lichenicolous fungi, specialist fungal parasites that have co-evolved with lichens. Lichens are fungi that have evolved a specialised mode of nutrition and are primary colonisers. They are common in all New Zealand landscapes, from inner-city footpaths to the summit rocks of Aoraki Mt Cook, and cover surfaces as diverse as rock, tree bark and buildings. Although tolerant of a wide range of ecological conditions lichens are extremely sensitive to atmospheric and terrestrial pollution and have an important use as bio-monitors of environmental health and change. Lichens are important in grassland and forest ecosystems as major nitrogen fixers, acting as biological fertilisers and they have potential value in processes of ecological repair and restoration. Flora of New Zealand: Lichens discusses 1706 taxa in 354 genera. Keys to genera cover foliose, squamulose, fruticose, filamentous, placodioid, leprose, crustose, foliicolous and lichenicolous life forms. All genera have descriptions, and commentaries provide up-to-date references. Species descriptions discuss thalline, apothecial and chemical characters, and a biogeographical grouping is given. All names based on New Zealand material are typified, both homotypic and heterotypic synonyms are listed, and the provenance of type material is indicated when known. An index to accepted taxa and to synonyms is provided plus a bibliography.