Received: 31 December, 2010. Accepted: 20 December, 2012. Invited Review Floriculture and Ornamental Biotechnology ©2012 Global Science Books Taxonomy and Phylogeny of the Genus Lilium Veli-Pekka Pelkonen * • Anna-Maria Pirttilä Department of Biology/Botany, University of Oulu, P.O. Box 3000, FIN-90014 Oulu, Finland Corresponding author: * veli-pekka.pelkonen@oulu.fi ABSTRACT Lilies have a long history as ornamental plants. Today, there is an ever increasing variety of new lily cultivars due to the significant progress in the propagation and development of new methods in breeding. The domesticated native species have retained their place along with new hybrids in commercialized horticultural industry, and they have sustained their invaluable potential for the breeding of new cultivars for garden use as well as for greenhouse culture. Systematics has always played an important role in plant breeding, giving guidelines for hybridization, although biotechnology has introduced new solutions for many problems that were evolutionary obstacles especially in inter-specific crossings before. The genus Lilium has been a subject of variable suggestions for classification systems, and the process still continues. The currently accepted concept for the phylogenetic and taxonomic system for all species is based on geographical, structural and genetic information. In our review, we give an insight into the latest progress in revealing the taxonomical relationships within the genus. According to the existing GenBank sequence data, we have constructed a phylogenetic tree consisting of the main species and sections of the genus. Provided with species photos, the tree gives a brief overview of phylogeny- and morphology- based classifications, which are not always congruent. In the tree mainly all species grouped into sections defined within the genus, but L. bulbiferum and L. dauricum grouped equally with the species in Sinomartagon and not with each other. Even though these two species share many morphological features, the phylogenetic tree questions the existence of the section Daurolirion and potentially gives a blueprint for classification in the future. _____________________________________________________________________________________________________________ Keywords: bulbous plants, classification, lilies, systematics CONTENTS INTRODUCTION.......................................................................................................................................................................................... 1 TRADITIONAL OR HISTORICAL CLASSIFICATION............................................................................................................................. 2 HISTORY AND THE CRITERIA OF CLASSIFICATION ........................................................................................................................... 2 GENOME SIZE AND ORGANIZATION OF LILY SPECIES ..................................................................................................................... 3 FROM STRUCTURE TO GENOME AND CLASSIFICATION .................................................................................................................. 3 MOLECULAR EMPHASIS IN TAXONOMIC STUDIES ........................................................................................................................... 3 NEW ASPECTS ON THE CLASSIFICATION OF LILIUM......................................................................................................................... 5 Martagon ................................................................................................................................................................................................... 6 Pseudolirium (American group) ................................................................................................................................................................ 6 Archelirion (Oriental group) ...................................................................................................................................................................... 6 Liriotypus (Candidum group) .................................................................................................................................................................... 7 Sinomartagon (Asiatic group) ................................................................................................................................................................... 7 Leucolirion (Trumpet group) ..................................................................................................................................................................... 7 Daurolirion (L. bulbiferum and Dauricum group) ..................................................................................................................................... 7 CONCLUSION .............................................................................................................................................................................................. 7 ACKNOWLEDGEMENTS ........................................................................................................................................................................... 7 REFERENCES............................................................................................................................................................................................... 8 _____________________________________________________________________________________________________________ INTRODUCTION Lilies (genus Lilium L.) have retained their position as one of the most important ornamental plant group both as garden plants as well as pot cultured and cut flowers. The genus consists of approximately 100 species that range from the Sierra Nevada and Rocky Mountains to eastern North America through Europe and Middle East to the Caucasus Mountains, Siberia, and Eastern Asia. The only continents devoid of endemic Lilium species are Africa, South America, Australasia and Antarctica (Woodcock and Stearn 1950; Rockwell et al. 1961). The natural distribution of the genus suggests that the main speciation occurred after the separation of the land masses that later formed the present continents of Eurasia and North America, and that the main species groups of the early classification were established mainly based on the geographic isolation. Although the structural differences as well as the geographical distribution of the species are vari- able, the genome structure on karyotype level is sur- prisingly constant throughout the genus. Haploid chromo- some number is invariably 12, and polyploidy is almost non-existent in natural populations. Although there are differences in the genome sizes between species, the com- mon feature is the exceptional size, ranging from 32 to 100 billion bp (Bennett and Smith 1976; Sentry and Smyth 1989; Siljak-Yakovlev et al. 2003). In record, the oldest garden plant is L. candidum L., which has been grown for its decorative value since the ancient times in Egypt and Middle East. Lilies have had their place also in European ®