This report advices which native species of the genus Rosa and autochthonous material should be included in the gene bank for native trees and shrubs in Flevoland based on information on the distribution of the species, recent knowledge about taxonomy and genetic information.

This is an attempt to outline a consensus taxonomy for the dog-roses (Rosa sect. Caninae) of northern, western and central Temperate Europe, including the British Isles, by combining the characteristics of the main British and Continental systems in use today. It involves adopting the slightly narrower species concept of the Continent with the wider recognition of hybrids followed in Britain. The proposed system is based on the traditional view of species of dog-roses; it is considered premature to attempt a ‘phylogenetic’ system based on the highly fragmentary data that are so far available.

Urban trees form a vital component of sustainable cities but the use of a restricted range of species and genotypes may pose a risk to global biodiversity. Despite several studies investigating tree species diversity, intraspecific genetic diversity of urban trees remains largely unexplored. Here, we characterized the genetic diversity of Tilia × europaea, one of the most widely planted urban tree species in Northwest Europe. We compared the genotypic diversity of historical plantings of Tilia spp. from the 17th century with the genotypic diversity of currently available planting stock in Belgium and the Netherlands. In total, 129 trees were sampled and genotyped with 14 microsatellite loci and 150 polymorphic Amplified Fragment Length Polymorphism markers. In Northwest Europe, homogenization of urban T. × europaea plantings already started at the 17th century. Genetic diversity within contemporary commercial planting stocks was extremely narrow and consisted mainly of two clones, sold under the name ‘Pallida’ and ‘Zwarte linde’. The genetic diversity found within the historical plantings was about four times higher than in the current commercial planting stocks. We recommend that tree nurseries should enlarge the genetic diversity of T. × europaea commercial planting stocks. The old clones have shown long-term disease resistance and could provide tree breeders with the valuable new genetic material. The range of available Tilia species and genotypes needs to be explored in future urban tree planning to optimize desired ecosystem services.

Dit artikel in boekvorm biedt nieuwe inzichten in het complexe geslacht Rosa L. en presenteert een systematische bewerking van de in Nederland in het wild voorkomende rozensoorten. In inleidende hoofdstukken worden de cultuurhistorie, biologie, morfologie, genetica, taxonomie en ecologie van rozen behandeld, daarnaast wordt het natuurbeheer inzake de bescherming van de wilde rozensoorten bediscussieerd en een voorstel voor een Rode Lijst gepresenteerd. Tweederde van de in Nederland inheemse rozensoorten komt in aanmerking voor plaatsing op deze Rode Lijst. Het artikel geeft bovendien een overzicht van de geschiedenis van het rozenonderzoek in Nederland. De systematische bewerking omvat een algemene bespreking van het geslacht, de secties en subsecties, en beschrijvingen van de 26 rozen soorten die in Nederland in het wild voorkomen, inclusief bijbehorende lijntekeningen, foto’s en verspreidingskaartjes; van deze 26 soorten zijn er 17 inheems met autochtone populaties. Dit hoofdstuk wordt voorafgegaan door een determinatiesleutel voor deze 26 soorten. Rozen zijn polyploid. Van de 26 in Nederland in het wild voorkomende rozensoorten behoren er 17 tot de sectie Caninae (inclusief de neofyten Rosa glauca en R. villosa). Deze groep omvat genetisch gestabiliseerde hybridogene soorten. Alle soorten van deze sectie zijn van allo poly ploide oorsprong. Binnen de soorten van de sectie Caninae is de morfologische en genetische variabi liteit groot. Bovendien worden alle soorten in deze sectie gekenmerkt door een afwijkende vorm van meiose (de canina-meiose), waardoor bij de nakomelingen het merendeel van de chromosomen en de meeste onderscheidende kenmerken van de moeder afkomstig zijn (matroclinie). Een aantal voor de determinatie belangrijke kenmerken worden echter via de vader overgeerfd. Na twintig jaar veldonderzoek aan rozen in Nederland, Duitsland en Belgie, een grondige orientatie op de Europese literatuur en consultatie van internationaal vermaarde rozenexperts hebben de auteurs gekozen voor de soortomgrenzingen van Henker in de Illustrierte Flora von Mittel europa.1 Henkers benadering volgt een gulden middenweg tussen splitters en lumpers en zijn soortomgrenzingen zijn vrijwel gelijk aan die in de Duitse Standaardlijst2 en de Atlas Florae Europaea.3 Zij wijken echter af van de soortomgrenzingen die in onder meer Heukels’ Flora van Nederland4 en de Belgische5 en Engelse Flora6 worden aangehouden. Tijdens het veldonderzoek en de revisie van herbariummateriaal zijn vijf nieuwe rozensoorten voor Nederland gevonden: Rosa henkeri-schulzei, R. inodora, R. nitida, R. pseudoscabriuscula en R. subcanina. This paper provides new insights in the complex genus Rosa L. and presents a systematic treatment of the wild roses of The Netherlands. It gives an overview of the cultural history, biology, morphology, genetics, taxonomy, and ecology of roses and discusses nature conservation issues concerning wild rose species; a proposal for a Red List is included. The paper also presents an overview of the history of rose research in The Netherlands. The systematic treatment includes species descriptions, illustrations, photos, and distribution maps of the 26 species of roses occurring in the wild in The Netherlands, of which 17 are indigenous with autochthonous populations. This section is preceded by a key for these 26 species of wild roses. Roses are polyploids. Seventeen species among the 26 rose species occurring in the wild, including the neophytes Rosa glauca and R. villosa, belong to the section Caninae. This group contains genetically stabilised hybridogenic species. All species of this section are of allopolyploid origin and show tremendous intraspecific variability in morphology and genetics. In addition, all representatives of the section Caninae are characterised by a form of unbalanced meiosis (socalled ‘canina meiosis’), by which most chromosomes in the offspring have a maternal origin and offspring traits are primarely derived from the mother plant (matrocliny). A few taxonomically important characters, however, are inherited paternally. After twenty years of field research in The Netherlands, Germany and Belgium, a thorough study of the European literature, and consultation of several international rose taxonomists, the authors adopted the species delimitations in roses used by Henker in the Illustrierte Flora von Mitteleuropa1, which closely resemble those used in the German Standard List2 and the Atlas Florae Europaea.3 Although Henker’s species delimitations differ from those used in Heukels’ Flora van Nederland4, and the Belgian5 and the British Floras6, his approach represents a perfect compromise between splitters and lumpers. Revision of herbarium material and field inventories resulted in finding five rose species new to The Netherlands: Rosa henkeri-schulzei, R. inodora, R. nitida, R. pseudoscabriuscula, and R. subcanina.

Despite extensive forest destruction in the Middle Ages and later intensive commercial forest management, remnants of virgin forests remained spared in some Central, Eastern and South-Eastern European countries. These virgin forests are the last examples of original forests in this part of Europe. That is why their protection becomes an important issue of current European forestry and nature protection policy. But the knowledge about the location and the area of virgin forests in these countries is incomplete up till now. This article has the prime goal to present a conceptual framework what virgin forests might be ("A conceptual framework for defining of virgin forests" section). Based on this framework, a working methodology has been tested in Bulgaria and Romania ("Results of the two national projects in Romania and in Bulgaria" section and further). For this reason two projects have been carried out by the Royal Dutch Society of Nature Conservation (KNNV) in close co-operation with the Forestry Institutes in Romania and in Bulgaria. The results of these projects are described in general terms and further analysis in the future is necessary to describe specific features like forest structure and spatial heterogeneity of these forests. Based on the results of the inventory, principles of sustainable protection and management of the mapped virgin forests were defined and described in the research reports. The usefulness of the inventory became evident already during the EU pre-accession period of both countries while preparing the NATURA 2000 network. The remaining virgin forests of temperate Europe are an inexhaustible source of ecological information about biodiversity, structure, natural processes and overall functioning of undisturbed forest ecosystems. Their research will reveal information which can be used for ecological restoration of man-made forests which are degraded through intensive forestry practices over the last centuries. The last virgin forests of temperate Europe represent an irreplaceable part of the natural capital of Europe and are worth to be protected by law. Their last remnants in South-Eastern and Eastern Europe are endangered by commercial activities. A full inventory of remaining virgin forests in all countries of temperate Europe is a matter of highest urgency. A representative selection of virgin forest sites should be declared by UNESCO as World Heritage Sites.

The genus Rosa has a complex evolutionary history caused by several factors, often in conjunction: extensive hybridization, recent radiation, incomplete lineage sorting, and multiple events of polyploidy. We examined the applicability of AFLP markers for reconstructing (species) relationships in Rosa, using UPGMA clustering, Wagner parsimony, and Bayesian inference. All trees were well resolved, but many of the deeper branches were weakly supported. The cluster analysis showed that the rose cultivars can be separated into a European and an Oriental cluster, each being related to different wild species. The phylogenetic analyses showed that (1) two of the four subgenera (Hulthemia and Platyrhodon) do not deserve subgeneric status; (2) section Carolinae should be merged with sect. Cinnamomeae; (3) subsection Rubigineae is a monophyletic group within sect. Caninae, making sect. Caninae paraphyletic; and (4) there is little support for the distinction of the five other subsections within sect. Caninae. Comparison of the trees with morphological classifications and with previous molecular studies showed that all methods yielded reliable trees. Bayesian inference proved to be a useful alternative to parsimony analysis of AFLP data. Because of their genome-wide sampling, AFLPs are the markers of choice to reconstruct (species) relationships in evolutionary complex groups.

Distinguishing between the indigenous and non-indigenous character of tree and shrub species is problematic because of trade, transfer and planting during the past centuries. Palaeobotanic research and research of written sources and toponimes have shown the indigenous character of approximately 100 woody plants (excluding brambles). The author has developed a method with a number of criteria, to measure the indigenous nature of specific trees or bushes. Original indigenous trees and shrubs are found especially in old forest areas, in old hedges, along meandering streams etc. They have survived through the centuries as polarded or coppiced trees, or by means of forest management in the past, in such a way that the fruits or grafts of the region are used. The large scale planting of plant material from other flora-regions results in a process of flora-falsification, and which is a serious threat for rare and extinguishing indigenous populations. The author argues for the use of indigenous plants in forest development as a contribution to conservation of nature and genetical biodiversity.