Historical overview - Belgium
Two undisputed personalities dominate the lichenological world in Belgium around the mid XIXth century: M.-A. Libert and J. Kickx. M.-A. Libert (1782-1865) worked in the Malmédy region, which at that time belonged to Germany and was later incorporated into Belgium by the Versailles treaty (1919); this explains why her results were not mentioned in the 'Prodrome de la Flore de Belgique' published beforehand (De Wildeman 1898). Whilst the four magnificent exsiccata fascicles she dedicated to the cryptogams found near Malmédy contain very few lichens, her herbarium, now housed at BR, has many, most of them collected and processed with great care and demonstrating how astonishing the lichen biodiversity of the area was at that time. Except for a few specimens, her herbarium remains to be studied. No doubt such a study would result in several changes to the current checklist: species new for the study area are expected to be found, but most should unfortunately appear as extinct since then.
Although his herbarium (now preserved in GENT) is also of tremendous interest, the work of J. Kickx (1803-64) is mainly composed of two most remarkable publications: a monograph of the 'Graphidées' found in Belgium (1865), and especially his 'Flore Cryptogamique des Flandres' (1867), a posthumous work which still is the only complete lichen flora to have ever been published for a part of the territory dealt with in this checklist.
It would be unfair not to mention two other Belgian botanists of that period. Firstly, Father F. J. Germain (1818-60) who collected near Bastogne and, in 1855, published romantic sentences like the following, speaking about Lobaria pulmonaria and Lobarina scrobiculata: 'The Ardenne forests which have rather old trees allow the botanist to harvest plentifully those nice lichens, near which it is impossible to pass along without at least an admiring glimpse'. For the whole of Belgium and Luxembourg, there are now at best 40 trees on which the first species can be observed, sometimes in quite low quantities. Near Bastogne, all forests are now spruce plantations with almost only the ubiquitous Hypogymnia physodes.
Secondly, Father E. Coemans (1825-71), who issued an all the more interesting set of exsiccata of Belgian Cladonia ('Cladoniae Belgicae Exsiccatae') as the material was mainly collected in the lower parts of Belgium ('Basse-Belgique' and 'Moyenne-Belgique') which are now very poor in lichens.
During the last decades of the XIXth century, railway construction, especially in the Meuse valley and through the Ardenne, opened up the exploration of those areas to leading botanists. In spite of the considerable losses they had suffered, those areas offer today the best localities for the rarest and most vulnerable lichen species. Those botanists published their results in scattered floristical notes, and most of their collections are now in BR. They are C. Aigret, C.-H. Delogne, C. Dens, A. Douret, G. Lochenies, E. Pâque, F. Pietquin and A. Tonglet (the latter asked for support to Father A.-M. Hue in Paris who published several species new to science on the basis of material he had collected near Dinant). This remarkable period came to an end with the publication of two major works: the monograph of Belgian Cladonia by Aigret (1901) and the chapter 'Lichens' in the 'Prodrome de la Flore de Belgique' published by De Wildeman (1898). The latter work is the first methodical inventory of all lichens known in Belgium and still is an indispensable reference for any floristic work on those organisms in the country.
Towards the end of the thirties, P. Duvigneaud (1913-91) started his studies, particularly with the publication of his 'Catalogue des Lichens de Belgique', written in collaboration with L. Giltay (Duvigneaud & Giltay 1938). Just like the 'Prodrome' of De Wildeman, this catalogue is an invaluable reference, though it is a mere uncritical compilation of data extracted from literature and devoid of any chorological or ecological information. Between 1937 and 1952, P. Duvigneaud published many notes on Belgian lichens, especially a fascinating review of epiphytic cryptogamic communities (Duvigneaud 1942).
Early in the sixties, several botanists at the University of Liège started research on Belgian lichens, particularly with detailed studies on the use of lichen acids in taxonomy. The publications of J. Lambinon clearly dominate that period; they are to culminate with his brilliant synthesis 'Les Lichens' (Lambinon 1969). This work includes thorough identification keys to the macrolichens of Belgium and Luxembourg. They still represent a key reference on that matter nowadays, and no doubt they stimulated many botanists to study those cryptogams, kept away from the main stream of interests of botanists in Belgium and Luxembourg for such a long time.
During the fifties and the sixties, German lichenologist T. Müller (1894-1969) was mainly interested in the 'Eifel' but extended his area of research into Belgium, especially into an area near Malmédy about which he published a short but very interesting note (Müller 1958). He eventually published a synthesis of his work (Müller 1965) which is also an invaluable reference. His herbarium had been inaccessible for a long time; it is not the case anymore and therefore it is now possible to examine the species he mentioned from the area studied in the present checklist. This should be done in the near future.