This Festschrift reflects perfectly the wide range of scientific interests of Harrie Sipman, an outstanding lichenologist contributing hugely to floristic and taxonomic research. Among the 29 papers, as might be expected, inconspicuous crustose groups in tropical areas such as Bacidia, Buellia, Caloplaca, Chapsa, Crypthothecia, Herpothallon, Lecidea s.str., Placopyrenium and Synarthonia feature strongly as well as papers on Cladonia and Xanthoparmelia. (There is even one paper exclusively on liverworts and hornworts.) There are excellent contributions on the taxonomy of ‘difficult genera’ and studies on the evolution of morphological traits in calicioid (Schistophoron) and cyanophilic lichens making it a valuable addition to the lichenologist's bookshelf. The papers also fittingly cover a wide geographical area with about half the articles being floristic studies ranging from an inventory of a biodiversity hotspot in Montenegro to additions to the checklists of Japan, Korea, Namibia, South Africa and the Seychelles. But most of these papers go far beyond purely floristic treatments and include descriptions of new species. Ecological insights are found in all of the papers although explicit focus on the ecology of lichens is given in only two papers. One of these two papers addresses the increase of Trentepohlia-containing lichens on exposed trees in the Netherlands as a possible result of global warming. The second ecological paper describes the composition and ecology of a species-poor but widespread new lichen community from gypsum crusts in the Namib desert, including the description of a new species of Buellia.

Lichenologists elsewhere may find some of the keys in this book useful. The paper by Aptroot et al. on “The lichen genus Herpothallon reinstated” has a key to the 29 species which includes a number of tropical byssoid crusts previously found in other genera such as Cryptothecia. The well-known red crust of southern USA and tropical S. America we used to call Chiodecton sanguineum is now Herpothallon rubrocinctum. Other keys include the newly delimitated genus Placopyrenium (Verrucariaceae), Sphaerellothecium (lichenicolous pyrenocarp), endolithic Lecidea with black apothecia (with species in a few related genera) and Cryptothecia and Stirtonia (Arthoniaceae) with some similar taxa and Haematomma in Thailand.

The strengths of this book are the high scientific quality of the papers and high standard of printing of the photographs (in colour where appropriate, such as sections of Lecideine apothecia and species of Herpothallon) in most of the papers. There is little to criticize. The weak points from our point of view are the use of bold print in some of the tables making the names unnecessarily difficult to read, as are the pixellated names in the phylogenetic tree presented in the paper on the evolution of cyanobacterial symbioses. There is no doubt that this book is a ‘must’ for most lichen taxonomists and a fitting tribute to Harrie Sipman who has contributed so much to lichenology including knowledge of the challenging tropical crustose species. Some lichenologists may be only interested in selected papers, but certainly for those having a world-wide approach to taxonomy, ecology and floristics especially the taxonomy of crustose lichens and extra-european biodiversity, it is very strongly recommended.