The macrolichen flora on trees in the Algarve is described on the basis of an examination of 105 main sites in the period 1970–76. 103 lichens are reported from the 43 phorophyte species studied, and discussions of the ecology and distributional patterns provided.

The weathering phenomena resulting from the encrustation of basalt by Pertusaria corallina have been studied by scanning electron microscopy and a variety of other techniques. The rock consists largely of plagioclase felspar (labradorite) and ferromagnesian minerals, the latter often being replaced by hydrothermally formed ferruginous clay minerals. Lichen weathering results in the extensive etching of the primary rock-forming minerals, particularly labradorite, and in the degradation of the clay minerals to yield a thin ochreous crust of poorly-ordered ferruginous (ferrihydrite) and alumino-silicate materials. These changes are brought about principally by the oxalic acid secreted by the mycobiont, a conclusion supported by observations following experimental mineral alteration.

At present 40 species of Pseudocyphellaria are recognised in the New Zealand flora, ten of which appear to be new and will be described elsewhere. In the present account, the 30 published taxa are listed alphabetically and, where applicable, the synonymy of confused species is discussed. The following 13 new combinations are made: P. coerulescens (Mont.), P. condensata (Zahlbr.), P. coriacea (Hook.f. & Taylor), P. delisea (Fee), P. dissimilis (Nyl.), P. hookeri (Church.Bab.), P. lividofusca (Krempelh.), P. moruagnei (Church. Bab.), P. multifida (Laurer), P. poculifera (Miill.Arg.), P. psilophylla (Miill.Arg.), P. pubescent (Miill.Arg.), and P. rubella (Hook.f. & Taylor). 85 taxa are reduced to synonymy with known species.

A simple scale using tropical lichen species has been used by secondary school students to assess air pollution zones in Hong Kong. The distribution of lichens was found to be related to the sites of power stations, a desalting plant, and heavily industrialised areas. As in temperate climates, both complexity of growth form and numbers of species increase with distance from the sources of air pollution.

Lobes of Xanthoria elegans are shown to be engulfed by more rapidly growing neighbouring lobes, thereafter ceasing to grow, and the rate of lobe engulfment increases with thallus age. Similarly, growth can cease when lobes of adjacent thalli meet. Mature central areas of eroded thalli may regenerate lobes and resume growth. In Buellia coniops, B. russa and Caloplaca cirrochrooides, peripheral concentric zonation does not always correspond to a single year's growth, and one zonation effect is correlated with an unusually severe winter.

A lichen flora of Northumberland is presented; it accepts 589 species. During the preparation of this work 7 lichens new to Britain and 271 new to the county were discovered. Complementing the species inventory is an analysis of factors affecting lichen distribution, a description of the major lichen habitats and a section on the history of lichen recording. Extensive tracts of semi-natural vegetation, steep climatic gradients and some of the least polluted air in England provide conditions suitable for a rich lichen flora; 40% of the British species have been recorded. Particularly notable habitats are sandstone crags in the uplands, Whin Sill (basalt) outcrops and sites contaminated with heavy metals. The County contains a major parkland, and several sites with a lichen flora characteristic of ancient woodland. A short list of lichenicolous fungi is included.