A detailed taxonomic survey of the saxicolous European species of Buellia based on a detailed survey and assessment of the important features of the genus is presented. These include the conidia, the anatomy of the exciple, the spore wall pigmentation, ornamentation and internal wall thickening, as well as analysis of the lichen substances. As a result, 36 saxicolous species are recognized, of which Buellia griseosquamulata and B. longispora are new taxa and B. atrocinerella and B. parvula are new combinations. Buellia coniops, B. lecideina and B. punclata are transferred to the validated genus Amandinea. A key to 43 accepted species of Buellia, Amandinea and Hafellia is included.

The lichen Lecanora schistina (Nyl.) Arnold has two kinds of conidia: filiform microconidia and obpyriform macroconidia. Both appear mixed in the same conidioma, the former being much more abundant. Sometimes these conidiomata contain a third type of conidia (microconidia) belonging most probably to a lichenicolous coelomycete living in the conidiomata of the lichen.

Nimisia fuegiae Kärnef. & Thell gen. et sp. nov. is described from Argentinian Tierra del Fuego. The new lichen differs from possibly related groups within the Parmeliaceae in unique anatomical characters, i.e. a medullary layer composed of extremely thick and strongly gelatinized periclinally arranged hyphae and a lower cortex composed of only a few layers of strongly pigmented, rather large cells. Ascus characters support its position in the Parmeliaceae. The new genus, which is named in the honour of its first discoverer, is discussed in relation to several other well-investigated members of the family.

Following a nationwide survey, the lichen vegetation associated with chalk grassland in England is described. The flora can be divided into species associated with flints (78 spp.), those found on chalk pebbles (65) and those occurring on the ground (72). Factors governing the distribution of the species were investigated. An important determinant of the flint assemblage is the degree of surface leaching, which is linked to stability; large flints embedded in turf are particularly rich. Chalkpebble lichens reach their maximum development at sites where faulting or other influences have hardened the substratum. Terricolous species have rather specialized requirements, being favoured by stresses associated with nutrient depletion, past disturbance, soil compaction, drought, rabbits, trampling by shoes (rather than hooves), and the presence of a small loess fraction in the soil. On both a national and a local scale, climate has been demonstrated to affect the distribution of certain species. Guidelines on the assessment of localities for conservation are provided and used to identify elite sites. A recent decline in the extent and species diversity of terricolous communities is giving cause for concern. Management requirements for conservation are discussed. They include recognizing the importance of intermittent disturbance; most of the richest sites are less than a hundred years old. The lichen flora has affinities with that present in urban areas. The survey provides an example of the importance of historical factors in determining the ecology of lichen communities in the cultural landscape.

Eleven stands of umbilicate lichens exhibiting a range of variabilities in enzyme banding patterns were compared on the basis of the ultraviolet (UV)absorbing properties of thallus extracts. Stands of Umbilicaria veilea, which were some of the most variable enzymatically, had the lowest UV absorbancy in extracts, and stands of Lasallia papulosa, which were among the least variable enzymatically, showed more UV absorbance than others. Umbilicaria deusta, U. muhlenbergii and U. mammulata had intermediate levels of absorbance. Negative correlations (P = 005–007) were found between enzyme polymorphism and UV absorbance in the ranges 215–220, 269–271 and 304–305 nm. There was also a significant negative correlation at P = 003 between enzyme variability and thallus dry weight extractable with either ethanol or acetone.

The effect of Paraquat, a herbicide known to stimulate oxygen-centred free-radical production in green plants, is compared with visible injury symptoms due to air pollution in Parmotrema reticulatum, an SO2-sensitive lichen species. This is in order to verify the hypothesized SO2 toxicity mechanism via the generation of free radicals. A new SEM-visible symptom is described: the production of heavy crystalline deposition on the thallus surface in SO2-stressed and Paraquat-treated specimens. The examination of the crystalline deposition by X-ray diffraction, correlated with SEM studies, showed that it is calcium oxalate (weddellite).