Introduction 2

Revision of the lichens of the Netherlands. I. Parmeliaceae by R.A. Maas+Geesteranus (Rijksherbarium, Leiden) (Pre-issued separately on 19. XI. 1947). Contents Page _ INTRODUCTION 2 1. Aim of the work 2 2. Distribution of the lichens 2 3. The taxa subordinate to the species 3 4. and chemicals Measuring 5 Herbaria 5. 5 GENERAL PART 7 CHAPTER I. Survey of the historical development of lichenology in the Netherlands 7 1. Collections 7 2. Literature 8 a. Seventeenth century 9 b. Eighteenth century 12 Nineteenth c. century 16 Twentieth d. century 28 3. Summary 36 References 37 CHAPTER II. of technical Glossary terms 41 References ■, 53 TAXONOMICAL PART . ; 61 Parmeliaceae 1. Candelaria 61 2. Parmeliopsis 64 3. Parmelia 69 4. Cetraria References concerning tlio geographical distribution of tho Parmeliaceae in Europe 188 Index Introduction 1. Aim of the work. has been of the Up to now there no modern flora Netherlands' lichens. In fact, the only lichen flora ever written in Holland (by H. C. van Hall) 1840. dates back as far as Anybody wishing to become acquainted with the of fact native lichens has to use foreign works. This is, course, a which in itself is not objectionable, but, whereas already before the war it was quite a problem for a private person to collect the most important works out of the multitude of the widely diffused literature, under the present conditions this is entirely out of the question. So much the more Dutch treatise. It is there a reason for attempting to write a may, therefore, cause some surprise that this work has not been written in Dutch, but this is due to the fact that that language is not generally known abroad. It is commonplace to state that progress in science is impossible without inter- nationalintercourse, and I don't think that it can be denied that lichenology in the Netherlands is badly in need of some foreign contact! On the other hand, I do hope that, because of its being written in a universal language, the present work will contribute to a better knowledge of the geographical distribution of the lichens. 2. Distribution of the lichens. For the sake of the Dutch student who is also interested in the distribution of the lichens outside the Netherlands, in broad outline the occurrence in Europe has been added to every species. I have restricted myself to this continent, since of a great number of species the data service the distribution at my concerning extra-European are too few or too uncertain. But even of the European countries I have no data at all from Latvia, whereas only very little and mostly old-dated literature is known from Albania, Great Britain, Greece, Luxemburg, Spain, and the U. S. S. R. (the republic Lithuania inclusive). The data of the distribution have not based of been on an investigation the material, as the Rijks- herbarium has not the disposal of such a detailed collection, but have exclusively been drawn from literature. If there existed a modern treatise with dealing a particular country, I have entirely relied upon that work. In other I have cases, gone through the most important papers without the aiming at completeness; older papers, for instance, have as a rule not been considered in this respect. The references concerning the distribution have been inserted the end of this at paper, p. 188. R. A. MAAS GEESTERANUS: Rev.- Lich. Netlierl. 1. Parmeliaccae 3 3. The taxa subordinate to the species. In few groups of plants the number of varieties and forms described is as vast as it is in lichens. It is true that several authors have been so prodigal in creating new varieties that a tangle rather than a surveyable system was the result. On the other hand, there are others who, mindful °f this to the deterrent, pay little attention or even neglect significance of the variability. I shall try to take an intermediate course between both views. There forms of are two ways in dealing with the varieties and a species. In the first and, in followed it is at least lichenology, most one, the of the which type specimen species occupies a predominant place both 111 attitude of mind and in description. The "specific" description is an extensive and detailed type description really, and, likewise, the varietal descriptions are type diagnoses of lower rank. In the other method, the species is split up into varieties (and forms); the type does not dominate any longer, having the same rank as any variety. Whether the type subdivision (i. e. the taxon including the type) should be called "var. typica” or another name, will be discussed further on - The specific description is, and by continuous emendation remains, so wide as to include all varieties, whereas in their turn the varietal descriptions comprise all forms, including "f. typica”. the and of both methods have been discussed Though pros cons already »y Rec. Trav. vol. Lanjouw (in Dot. Neerland., 29, 1932, p. 3C—46), I should like to return to this subject, since I have arrived at a different view. It is that in the first-named the true following method, species may '' e sharply discriminated one from another, whereas the "specific" description remains unaltered however many new varieties may be found afterwards. A serious objection, however, is the inconsistency of the subdivision of the If is into and species. a family split up genera, a genus juto the be subdivided species, one may logically expect species to entirely mto its varieties (and forms). Why should the type subdivision not have a name of its own? Some adherents to the method under discussion have clt right enough the need-to designate plants, which do not differ from le type specimen, by a special name in order to mark them from the vari eties, if a is concerned. particularly polymorphous species Now, my jection is that have done such they so by using terms as "planta typica, lp °, the .type, typical form, the species, le type, forme typique, l'espece, T ypus, typische Form, Normalform, Grundform, Hauptform, Ilaupttypus, auptart, Stammform". May not one, in view of these instances, expect a scientific and more uniform term in taxonomy? And how inconsistent, is this amegiving, for if the type of the species is designated by one of these ames, then "Normalform" why not assume a or a "forme typique" for the ypc of the variety? Besides, a good deal of the names mentioned above rongly convey the impression either that the type of the species essentially occupies a central place, around which the varieties are sub- 4 BLUMEA VOL. VI, No. 1, 1947 "normal" whereas ordinately arranged, or that it is the variety (form), the other are derived ones. "Why should the type be so strongly emphasised, why should it be considered normal, what is normal about the type, and what characters entitle the other varieties to be called "derived"? The real conditions be different. Within the may entirely "Formenkreis" of the entire species, the type of the species, whose only is due discovered special position to the fact that it has been first, may well be excentric "derived" characters very an fraction, having more than other It is that this the any variety. quite possible type (or group of closely related forms including the type), being adapted to a more has a smaller area than of the extreme environment, any variety same isn't it rather other species. Finally, superfluous to point out that names such as "the species", "Ilauptart", are positively wrong? The type is the starting-point, but it is inadmissable so far specimen to go as to identify plants of its affinity with the whole species. the second By method, it may in some cases be difficult to delimit certain the species, as originally simple image of the type may become blurred by the superimposed images of the varieties. The specific has be description, moreover, to emendated every time a variety is added severed. I admit that it or fully is a somewhat cumbersome way to designate with a specimens quaternary name, even a plant of the of the viz. affinity type, Parmelia cetrarioides var. typica f. eu-typica. other On the hand, the method is taxonoinically correct. The species is conceived be to a unit, composed of minor taxa which between them are equivalent, and is not wrenched from its context by the preponderance of On the type over the varities. reading the specific description, one is immediately and fully informed about the variability of the species concerned. These considerations have made me follow the second method, in spite of the objections stated above, and — a point which made me hesitate a long time — in spite of the nbmenclatorial changes which would necessarily be entailed. In the there foregoing has been some talk of "var. typica” as the of the subdivision. designation type It will be observed — perhaps not without some surprise — that this subdivisional name has not been used in the present paper. The reason is that, in accordance with Art. 16 of the International Rules of Botanical Nomenclature, I have always looked for the earliest for "var. epithet typica”. If this proves to be homonymous with the specific epithet, there is no objection whatever to accept it. In anticipation of the validation of the amendment to Recommendation XXXV proposed by (in Kew Bull., no. I Sprague 1939, 7, p. 324), fully agree with this author's view, viz. that the repitition of the specific epithet is to of preferable the use such terms as “typicus”, genuinus”, etc.

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