Leioderma subg. Fuscoderma D. Galloway & P. M. Jørg., is shown to be a distinct genus, confined to Tasmania and New Zealand and comprising three species: Fuscoderma amphibolum (Knight) comb, nov., F. applanatum (D. Galloway & P. M. Jørg.) comb, nov., and F. limbatum sp. nov. A key to the species is given. A revised key to Leioderma is also presented and a second locality (Ecuador) is reported for the Brazilian species L. glabrum D. Galloway & P. M. Jørg.

Sixty-two samples of Asahinea chrysantha from different localities in the Soviet Union were analysed by TLC. Three different chemotypes are recognised, each with a different geographical distribution. The most restricted of the three is an usnic acid deficient chemotype (I), with atranorin, alectoronic and α-collatolic acids, which is chemically the same as A. scholanderi and A. kurodakensis. Chemotype II contains usnic acid in addition to the basic chemistry, and chemotype III is α-collatolic acid deficient and has the widest geographical range. A centre of speciation of Asahinea in Soviet Primorje or Japan is proposed.

Twelve species of Rhizocarpon coexist with 94 other species of saxicolous lichens at Jonas Rockslide, Jasper National Park, Alberta, Canada. The position of each Rhizocarpon species in the community is assessed with respect to environmental factors and biotic relationships. Each species shows distinct correlations with measured environmental factors and a different set of interactions with other species. Rhizocarpon bolanderi and R. superficiale stand out as opposites with regard to their biotic associations and environmental correlations. Competition between pairs of Rhizocarpon species is predicted to vary in intensity, as some species pairs never occupy the same microenvironment, whereas others frequently occur in similar locations. Using thallus diameter as a measure, there is evidence of high recruitment rates into populations of the sub-genus Phaeothallus and lower recruitment rates in the sub-genus Rhizocarpon.

The present occurrence and vitality of Lobaria scrobiculata (Scop.) DC. were investigated at 67 localities (50 old and 17 new) in southern Sweden. Before 1950 L. scrobiculata was found at more than 300 localities in southern Sweden. However, it was only confirmed at two out of 50 thoroughly investigated old localities. An investigation of recently found localities (new) and confirmed ‘old’ sites showed that there have been decreases in population size, thallus size, fertility, number of phorophytes, and cliff colonization. In southern Sweden today L. scrobiculata is confined to old deciduous trees in regions with comparatively low air pollution and a high relative humidity. Apothecia have not been found in southern Sweden since 1947, although in the past, fertile material was collected from 35 localities in this region. The author suggests that this species, like many other lichens with the cyanobacterium Nostoc as photobiont, is currently more endangered by air pollution than by any other human activity and that it is seriously endangered in the southern part of Sweden.

Lichens of the most highly stressful habitats in Sverdrup Pass, Ellesmere Island, Northwest Territories, Canada, were examined for reproductive structures, as were lichens of less extreme sites within the same landform features. The study areas included twenty-two stands in a calcareous erosional mountain system and two microhabitats within the ablation zone of a valley glacier. In the most limited stands in the erosional mountains 83% of the lichens were apotheciate species and 93% of these were represented by specimens bearing apothecia. On stressful rock surfaces in the glacier fellfield most species also produced sexual fruiting bodies.

Axenic cultures of lichen mycobionts and photobionts were assayed for biological ice nucleation activity (INA), a characteristic which has recently been discovered in some species of lichens collected from nature. Of 14 species of mycobionts, five showed nuclei active at −5°C or warmer, while none of the 13 photobionts tested had INA at that temperature. It appears that biological ice nuclei in lichens are produced primarily by the mycobiont. Rhizoplaca chrysoleuca had the greatest INA. Other lichen fungi showing warm temperature INA were Cladonia boryi, Cladonia rangiferina, Lecanora dispersa, and Pertusaria flavicans. Lichen INA may be involved in moisture uptake and/or frost protection.

Column and thin-layer chromatography revealed the presence of the following carotenoids in the thalli of seven lichen species from Ireland: α-carotene, β-carotene, β-cryptoxanthin, lutein, 3'-epilutein, adonixanthin, α-doradexanthin, canthaxanthin, astaxanthin, antheraxanthin, lutein epoxide, neoxanthin and violaxanthin. The total content of carotenoids ranged from 11.9 μg g−1 dry wt in Menegazzia terebrata to 21·3 μg g−1 dry wt in Usnea rubicunda.