Taxonomic importance of seed morphology in Gentiana (Gentianaceae) NINO DAVITASHVILI and GERHARD KARRER* Institute of Botany, Department of Integrative Biology and Biodiversity Research, University of Natural Resources and Applied Life Sciences, Gregor-Mendel Str. 33, Vienna 1180, Austria Received 18 October 2009; accept for publication 10 November 2009 The seeds of Gentiana show high diversity in size, shape and surface pattern. Until now, seeds of only a limited number of taxa have been studied in detail and their utility in the subgeneric classification of Gentiana has not been evaluated. In this study we investigated seed micromorphology of the poorly known sections Pneumonanthe, Frigidae and Isomeria. In order to evaluate the relevance of seed sculpturing for taxonomy, we selected qualitative characters of seed shape and testa ornamentation of all documented sections and performed cluster analyses based on presence and absence of coded characters. Several new scanning electron microscopy pictures of seeds provided a number of valuable characters for the subgeneric differentiation of Gentiana. The results of the cluster analyses of seed characters generally support the sectional classification given by former authors. However, the European Gentiana asclepiadea does not group together with other taxa of section Pneumonanthe, but clusters near to the strictly European section Gentiana. Gentiana froelichii, endemic to the south-east Alps and treated traditionally within section Frigidae, clusters together with taxa of the European section Ciminalis. Our results reveal that seed micromorphology supports the reassignment of some taxa incertae sedis within Gentiana. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162, 101–115. ADDITIONAL KEYWORDS: cluster analysis – scanning electron microscopy (SEM) – seed micromorphology – subgeneric classification – testa ornamentation. INTRODUCTION Data on features of seed micromorphology have been reported to be useful for taxonomy in numer- ous plant groups (e.g. Juan, Pastor & Fernández, 2000; Metzing & Thiede, 2001; Môro et al., 2001; Segarra & Mateu, 2001; Plaza et al., 2004; Adams, Baskin & Baskin, 2005; Song, Yuan & Küpfer, 2005). Seeds can provide relatively stable character sets which are valuable for comparative studies at every level of the taxonomic hierarchy. Most taxo- nomic studies of seed micromorphology involve two steps: (1) the description of seed testa characters and (2) the definition of seed types. In general, such descriptive ‘standardized’ work largely lacks the comparative aspect, especially in the case of large data sets. Utilization of the statistical approach for establishing different types of seeds is an exception rather than a rule in taxonomic literature. The genus Gentiana L. (Gentianaceae) comprises approximately 360 species distributed mainly in tem- perate, arctic and alpine habitats of the northern hemisphere. Gentiana was reduced several times since its first description as a result of the segregation of genera such as Gentianella Moench and Metagen- tiana T.N.Ho and S.W.Liu. Current infrageneric clas- sifications of Gentiana sensu Ho & Liu (2001) start at the subgeneric (Halda, 1996) or sectional (Pringle, 1978, Ho & Liu, 2001) levels, using simple characters of seed morphology and other features such as growth form, flower morphology, chromosome number, etc. The importance of seed morphology for taxonomic studies of Gentiana was pointed out by Kusnezow (1894), Müller (1982), Miège & Wüest (1984), Yuan (1993), Omer & Qaiser (1995), Halda (1996), Ho & Liu *Corresponding author. E-mail: gerhard.karrer@boku.ac.at Botanical Journal of the Linnean Society, 2010, 162, 101–115. With 6 figures © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 162, 101–115 101