Language: French, with trilingual abstract in English, German, and French
During the last seven years since the official start of the research, the authors scanned the territory of the Grand-Duchy of Luxembourg for non-indigenous tree species. The result they present in taxonomic order is a fairly exhaustive list of 234 taxa present in the field in the studied area, including 10 subspecies, 3 varieties, 6 hybridogenetic species, 14 interspecific hybrids and 1 intergenetic hybrid, of which 60 are Gymnosperms (including Ginkgo) and 174 are Angiosperms. Each tree taxon is listed by its scientific name followed by vernacular names in French, German, English and Luxembourgish (whenever existing). Moreover, for each one, the inventary provides information on its origin (geographical or artificial), its estimated frequency in the territory and the location of one or more typical specimen to be viewed as examples. Introductory chapters outline historical aspects as well as giving explanations pertaining to the methodology used and, among others, the tree, indigenousness and hardiness concept. The discussion deals essentially with the uses of introduced trees as well as systematical and phytogeographical aspects in relation to the continents of origin of the taxons listed. Concerning the frequencies, little more than one third of the trees listed have an occurrence of no more than 5 specimen, 39 of these occur only once. The best represented families are Pinaceae [with the genera Abies (10), Picea (7) and Pinus (9)] for the Gymnosperms, and Aceraceae and Rosaceae (11 genera and 33 taxa) with the genera Acer (14) and Prunus (14) for the Angiosperms. Two other taxon-rich genera are Magnolia and Quercus (9 taxa each). A taxonomic outline and two indexes (scientific and vernacular names) complete the article.