Leptogium imbricatum P.M. Jorg. sp. nov. and L. intermedium (Arnold)Arnold are established as the correct names for two fairly widespread, small species:L. imbricatum has an arctic–alpine distribution. Leptogium intermedium was previously mostly named L. minutissimum (Florke) Fr., the type of which is L. subtile (Schrader) Torss., a distinct species usually growing on rotting wood or debris. Leptogium magnussonii Degel. & P.M. Jorg, mainly from maritime rock outcrops in Norway and Sweden, is described as new. The species complexes of L. plicatile (Ach.) Leighton and L. schraderi (Bernh.) Nyl. are discussed. The differences between L. byssinum (Hoffm.) Nyl. and L. biatorinum (Nyl.) Leighton are given, and L. aquale (Arnold) P.M. Jørg. comb, nov., a taxon related to the latter, is considered to be a distinct species growing in mountain brooks in Central Europe. Leptogium rivale Tuck, is recorded as new to Europe, from Romania. Leptogium bellopratense Hy is shown to be a synonym of L. brebissonii Mont. New records for L. coralloideum (Meyen & Flotow) Vainio, L. massiliense Nyl. and L. rivulare (Ach.) Mont, are given.A preliminary key to the small European species (north of the Alps) is appended. The following names have been lecto– or neotypified: Collema byssinum Hoffm., Collema pulvinatum Hoffm., Leptogium bellopratense Hy., Leptogium crenulatum Watson, Leptogium massiliense Nyl., Leptogium minutissimum var. intermedium Arnold, Leptogium minutissimum f. plumbeum Zwackh ex Arnold, Leptogium pusillum var. aquale Arnold, Leptogium rivulare var. crenatulum Nyl., Leptogium scotinum var. crenatum Nyl., Lichen byssinus Hoffm., Lichen minutissimus Flöurke, Lichen schraderi Bernh., Lichen subtilis Schrader and Parmelia scotina var. lophaea Ach.

Biatora meiocarpa (Nyl.) Arnold (Lecanorales, lichenized Ascomycotina) is described and compared with some of its relatives, particularly B. helvola Körber ex Hellbom (syn. Lecideahelvola), a species with which it has often been confused. Biatora meiocarpa and B. helvola differ in (1) width of the paraphysis tops, (2) hymenium height, (3) apothecium width, (4) gelatinization of the paraphyses, (5) composition of the excipulum (hyphae with ellipsoid or shortly rectangular lumina in B. meiocarpa, narrowly linear lumina in B. helvola), (6) chemistry (1-2 triterpenoids or no substances in B. meiocarpa, gyrophoric acid plus 1-2 triterpenoids in B. helvola), and (7) length and shape of conidia. The variation in the first three characters overlaps but one–way analysis of variance (ANOVA) shows that B. meiocarpa and B. helvola differ significantly in each of these characters. Three further characters were subjected to ANOVA: spore length, spore width and length/width ratio of the spores. No statistically significant differences were observed in these characters.Biatora meiocarpa generally occurs on smooth bark of broad–leaved trees and shrubs. It is known from northern Sweden, Finland, and northwestern Russia

The new combination Amandinea petermannii (Hue) Matzer, Mayrh. & Scheidegger; is proposed. The taxonomy, morphology, anatomy, chemistry, ecology and distribution of this lichen are discussed. Rinodina convoluta D. C. Lindsay is synonym of A. petermannii.

The pinkish galls on Usnea, often called Biatoropsis usnearum are shown to represent basidiomata of a previously unrecognized genus of heterobasidiomycetes with transversely septate basidia, to which the generic name Biatoropsis can be applied. The new genus is tentatively included in the Platygloeales. The hyphomycetous anamorph strongly resembles the genus Hormomyces. Biatoropsis usnearum is very frequent and widely distributed on Usnea, but has also been collected on Protousnea; the galls have been found parasitized by Abrothallus usneae and three species of Lichenoconium. Two other heterobasidiomycetes growing on Usnea are described: Tremella santessonii Diederich sp. nov. from Africa has transversally 1- septate basidia; T. stevensiana Diederich sp. nov. from Australia has longitudinally 1-3-septate basidia and a type of hyphomycetous anamorph poorly known in other species of Tremellales. Several other Tremella–like or gall-forming fungi on Usnea are briefly discussed.

Nylon mesh litter–bags markedly reduced the rate of weight loss of lichen litter, as compared to unconfined (free) lichens, suggesting that herbivores and detritivores larger than the mesh size make a significant contribution to the disappearance of lichen litter. The half–life of free lichen litter was 1·5 months for Alectoria sarmentosa, 2·5 months for Hypogymnia inactiva, 3·5 months for Platismatia glauca, and 7 months for Lobaria oregana. The half–lives were 2·9 times longer for the same species in litter–bags. Because A. sarmentosa showed the greatest difference between free litter and litter–bags, we conclude that, of the four species studied, it had the highest rate of consumption by larger herbivores and detritivores.

Field experiments were conducted to test the effect of some agrochemicals on the growth of Cladonia furcata. Mineral fertilizer had no direct effect on lichen growth. In contrast, organic manure promoted the length of podetia. A lethal effect was recorded in the case of calcium cyanamide. In addition to direct effects of agrochemicals, indirect effects were also recorded.

A number of possible displacing agents have been tested for their ability to release extracellular bound lead from Cladonia portentosa. Metal cations (Ni and Cu), thiol–rich reagents (glutathione, ammonium pyrrolidinedithiocarbamate) and some chelating agents (EGTA, EDTA at pH 9·5 or pH 2·7) were ineffective or caused membrane damage. Disodium EDTA at pH 4·5 was found to be an effective displacing agent, although the Na caused some release of intracellular K without membrane damage. This displacement procedure showed that no Pb suppliedin the laboratory entered the protoplast in 2 h. The effect of Ca, Cu, Pb, and Sr on membrane integrity was investigated.