Dendrology: Cones, Flowers, Fruits and Seeds

Book Preface

Dendrology is the scientific study of the morphological characteristics of woody plants, their relationship, biological characteristics, ecological requirements, variability, distribution and economic importance. Reproductive organs of woody plants (cones, flowers, fruits and seeds) are extremely important when it comes to defining particular taxa with certainty. This book contains detailed descriptions and photographs of reproductive organs of the trees, shrubs and half-shrubs relevant for the European dendrology. The book is divided into 6 chapters. The introduction contains an overview of the morphology of the cones, flowers, fruits and seeds of gymnosperms and angiosperms, according to Krüssmann (1972, 1976), Weberling (1989), Sitte et al. (1998), Leins (2000), Farjon (2010), Hardin et al. (1996), Ronse de Craene (2010), Šugar (1990), Simpson (2010), van der Pijl (1972) and Nicolson et al. (2007). The aim of this chapter is to help the reader to understand the terms used in the description of certain taxa in the third chapter. Since a comprehensive overview of reproductive organ morphology would exceed the scope and purpose of this book, and there is already very valuable literature in this field, the introductory part provides a basic overview of morphological characteristics. For more detailed information, the reader is referred to the specialized literature on plant morphology. The second chapter provides the reader with a clear insight into the taxonomic position of all taxa included in this book, according to Cronquist (1981), Dahlgren et al. (1985), Kramer and Green (1990) and Farjon (2010). The third chapter comprises the largest part of the book, consisting of the descriptions and photographs of 2020 taxa, or more precisely, 845 species, 58 subspecies, 38 varieties, 13 forms, 40 hybrids and 1026 cultivars. These appear in the alphabetical order of their botanical names, beginning with the genus Abelia and ending with the genus Ziziphus, according to Zander – Dictionary of Plant Names (Erhardt et al., 2014) and the International Plant Names Index (IPNI), conforming to the International Code of Nomenclature for algae, fungi and plants (Shenzhen Code, ICN, Turland et al., 2018). The names of the authors of botanical names are standardized in conformity with Brummit and Powell (1992). Synonyms are also given, and in the case of taxa that are hybrids, parental species are listed. For every taxon, information is provided on the family to which it belongs, according to the classification from the second chapter. This is followed by the common name of the taxon. For gymnosperms, detailed descriptions of male and female cones and seeds are provided. For angiosperms, flowers, fruits and seeds are described in detail. Angiosperm flowers are, among other things, characterized as being ornamental or fragrant. A detailed description of flower morphology always begins with the description of the perianth, continuing (if the flowers are hermaphroditic) with a description of the male flower parts and then the female. If the flower in question is unisexual, the description of male flowers comes first, followed by the description of female flowers.

If flowers are part of an inflorescence, this fact is also mentioned, together with the position of the flowers or inflorescences on the plant. The last piece of information concerns the flowering time. The flowering and fruiting periods pertain to the Global North temperate zone, unless otherwise specified. When it comes to fruits and seeds, the information is given in the following order: description of fruits, number and description of seeds in the fruit, maturation period and the mode of fruit or seed dispersal. The reader will also learn if the fruits are decorative. The morphological description is followed by the information on the distribution range, i.e. on the area in which the species is naturally distributed. The order of photographs corresponds with that of the morphological descriptions. The greatest challenge in writing a book of this kind is definitely the selection of taxa. The taxa included in this book cover a wide area of European dendrology, with descriptions for 447 species of trees, shrubs and half-shrubs that are autochthonous in Europe. Aside from the more or less widely distributed and well-known species, some rare, endemic species are also described. In addition to autochthonous species, the book also includes numerous ornamental species cultivated in Europe but originating from other continents. Invasive foreign woody species, which endanger the biodiversity of European ecosystems, are also described. Furthermore, the book includes information on species that have been naturalized in Europe for a long period of time. The book also offers a description of many exotic woody species with edible fruits or seeds, which can be found in grocery shops. In addition to the species, the book includes numerous ornamental cultivars and hybrids, which are frequently cultivated in European gardens and parks. The names of cultivars are listed according to List of Names of Woody Plants, International Standard ENA 2016–2020 (Hoffman, 2016), conforming to the International Code of Nomenclature for Cultivated Plants (ICNCP, Brickell et al., 2016). The book includes cultivars that differ from the species and other cultivars of the same species in their flowers or fruits. The selection of cultivars had to be limited, given the fact that cultivars of certain taxa are so numerous that they are usually presented in separate monographs. In other words, this book contains information on some cultivars, in order to give the reader an impression of their appearance and abundance.

The information on plant breeders’ rights of cultivars and names protected as trademarks is not specified. That information should be checked with the official registration agencies. The groups are not specified, but can be found in Hoffman (2016). The best part of working on this book was definitely the fieldwork, i.e. the study and collection of plant material, as well as taking photographs. The photographs were taken in natural habitats or in parks, private gardens, botanical gardens and arboreta in Europe.

After the collection of cones and fruits and the separation of seeds, these were photographed with a millimetre ruler, to enable the reader to notice all of the important characteristics more easily. Photographs, totalling 6644, are an extremely important part of the book. The bibliography lists 575 references to the literature used from the field of dendrology and related sciences. The book is structured in such a way that the references are not cited in the first, second and third chapter, but instead the literature used in these chapters is listed in this chapter. It includes literature in English, German, Spanish, Slovenian and Croatian.

The index of botanical names and index of common names are given at the end of the book. The book was written for scientists, students and experts of different fields, whose work is related to woody plants – in other words, for those interested in dendrology, ornamental woody plants, botany, forestry, urban forestry, agronomy, horticulture, plant propagation and growing, landscape architecture etc. This is not a book that is exclusively popular or scientific, but rather a combination of the two, as it contains not only a detailed scientific description of reproductive organs of woody taxa, but also a large number of useful and potentially popular photographs of those organs. This means that anyone who does not need such detailed descriptions may use a part of the description, together with the photographs which it is hoped will be very useful to any reader.

The Faculty of Forestry at the University of Zagreb has enabled me to develop professionally and has provided me with the freedom and joy to work creatively, as well as with the necessary support, all of which has resulted in this book. I would like to thank the translator Ana Peričić for her help in the very demanding task of translating and proof-reading the text. I would also like to thank all my colleagues and loved ones who have helped me in any way while I worked on this book. The authors of almost all the photographs are Marilena Idžojtić and Željko Idžojtić.

I am thankful to the colleagues who have ceded me their photographs: Robert Brus (page 609: third column, first photograph), Márton Korda (page 227: second column, first photograph and third column, fourth and fifth photographs), Igor Poljak (page 219: second column, second photograph; page 294: second column, first and third photographs; page 298: second column, third photograph; page 524: first column, first and third photographs, second column, fourth photograph), Darko Posarić (page 608: third column, first photograph; page 609: first column, first to fourth photographs), John Seiler (page 717: second column, first photograph), Pascale Servais and Pierre Seba (page 400: third column, first photograph; page 401: first column, fifth photograph).

I would like to thank Mary Preep, editor at Elsevier, who has helped me with the project professionally and patiently from the proposal to its final realization. In my fieldwork,

I was greatly assisted by Željko Idžojtić, MEng, who is also responsible for the complete graphic design and layout of the book, for which I am most grateful.

I dedicate this book to my devoted parents and children.
Zagreb, June 16, 2018 Author