Language: French with bilingual figure legends, table heading, tables and appendix in English and French, and trilingual abstract in English, French, and German
Luxembourg is divided into two natural districts (Oesling and Gutland), the geological, geographical and climatic features of which are sketched. A short history of bryofloristic research is given. Two hundred squares of the former Institut Floristique Belgo-Luxembourgeois (4 × 4 km) were mapped, including the foreign part of those squares and 9 squares entirely situated in Lorraine (France). Field work between 1979 and 2010 yielded 22809 individual data points.
Luxembourg has now 601 different taxa of bryophytes (610, if border areas are included), comprising 140 liverworts and hornworts, which is about 87% more than at the beginning of the XXth century. 27 infra-specific taxa are recognized. Comments are given on species restricted to foreign border areas. A classification according to families shows the overwhelming importance of Pottiaceae (81 taxa). The phytogeographic spectrum shows the predominance of temperate European elements, but also a strong (sub) oceanic and boreal influence; orophytes make up to 36% of the bryophyte flora. The principal ecologies of bryophytes are shortly described, showing the importance of epiliths, which are favored by a great variety of rocky substrates. Most bryophytes happen to be rather rare; merely one out of eight taxa is common all over the country. A short comment is given on species evidently regressing or progressing.
Floristic richness (or biodiversity) is examined. A quantitative approach shows that a very small number of squares are rich; they are situated mostly in the Petite-Suisse area; southern Oesling and the Moselle valley are also areas where richness is above average. The average number of bryophytes per IFBL-square is 114, the mean is 107. Bryophyte richness is also examined in an international context. A more qualitative approach deals with the relation of the number of mosses to the number of liverworts (Lebermoosindex) and cites the richest and most complex natural sceneries. The bryological “hot spots” are also made out; they are based on three different criteria.
The distribution of the bryophyte taxa is commented and a few evident distribution patterns are described. The reasons behind these patterns are shortly sketched, whether they are natural (climate, topography, geology) or artificial (cultivations, pollution). An annotated checklist gives information, for every recognized taxon, on the year of first publication, its frequency, its ecology, further papers (only for rare taxa) and the Red List status. Individual numbered distribution maps are provided.