© CSIRO 2003 10.1071/BT02102 0067-1924/03/040459 www.publish.csiro.au/journals/ajb Australian Journal of Botany , 2003, 51, 459–469 CSIRO PUBLISHING Leaf epidermal microcharacters of the Old World species of Lotus (Leguminosae: Loteae) and their systematic significance Sebastián A. Stenglein A,B , Marta N. Colares A , Ana M. Arambarri A,C , María C. Novoa A , Claudia E. Vizcaíno A and Liliana Katinas A A Cátedra de Morfología Vegetal, Facultad de Ciencias Agrarias y Forestales, Universidad Nacional de La Plata, C.C. 31, 1900 La Plata, Argentina. B CICBA—Comisión de Investigaciones Científicas de la provincia de Buenos Aires, Argentina. C Corresponding author; email: anaramba@infovia.com.ar Abstract. Some perennial species of Lotus L. (Leguminosae: Loteae) from the Old World constitute an important forage resource. The epidermal microcharacters of 15 species belonging to the Old World Lotus angustissimus L., L. corniculatus L., L. creticus L. and L. peregrinus L. groups were described to compute the phenetic relationships, and to compare these results with previous classifications and phylogenetic hypotheses. Data on epidermal cells, stomata, stomatal indeces and trichomes were recorded and summarised in tables and illustrations. To test the taxonomic value of epidermal features and to establish the phenetic relationships, two numerical analyses were performed. Phenograms by the unweighted pair-group method (UPGMA) of clustering were generated. Results of the numerical analysis using a basic data matrix (15 operational taxonomic units × 15 epidermal characters) suggested that epidermal characteristics make it possible to establish species’ and species groups’ relationships; however, they were not totally coincident with previous classifications. An additional analysis using epidermal characters plus other morphological characters from leaves, flowers, fruits and seeds led to establish species’ and species groups’ relationships. Results generated by the latter analysis demonstrated that epidermal traits, together with other characters, are useful and informative for testing species clustering. Phenetic results coincide with earlier classifications and chromosome-number studies and accord well with a previous phylogenetic hypothesis in showing the close relationship among species of the Old World Lotus groups included in this study. BT02102 EpidermisofLotus S.A.St engl ein etal . Introduction There are 124 Old World species of Lotus L. (Leguminosae: Papilionoideae: Loteae) (Kirkbride 1999), some of them belonging to the Lotus angustissimus L., L. corniculatus L, L. creticus L and L. peregrinus L groups. These four groups contain Lotus corniculatus L. var. corniculatus, L. corniculatus L. var. japonicus Regel, L. glaber Mill., L. uliginosus Schkuhr. and L. subbiflorus Lag., which constitute an important forage resource in the countries where they are cultivated and/or naturalised (Kirkbride 1999). L. angustissimus L., L. collinus (Boiss.) Heldr., L. ornithopodioides L. and L. palustris Willd. were also established and show significant promise (Arambarri and Balatti 1999). Throughout the years different authors have revised the classification of the Old World species of Lotus. Brand (1898), in the first Lotus monograph, considered that the genus comprised a number of complicated species groups (Formenkreise), often rendering delimitation of taxa within the groups rather difficult. He created two subgenera, the subgenus Pedrosia Lowe with the two sections, Heinekenia Webb and Eupedrosia Brand, and the subgenus Edentolotus Brand with five sections, i.e. Krokeria Moench., Xantholotus Brand, Erythrolotus Brand, Ononidium Boiss. and Quadrifolium Brand. The section Xantholotus contained a relatively high number of species that were distinguished from the species of other sections by the terete and laterally compressed fruits and yellow flowers. This section has been extensively studied, probably because it contains the most productive species of the genus. As a result, the species and varieties within section Xantholotus have been subject to frequent taxonomic changes. Heyn (1966) grouped some species of sect. Xantholotus into Lotus peregrinus L. (Heyn 1966), L. creticus L. (Heyn and Herrnstadt 1967) and L. angustissimus L. (Heyn 1970) species groups. Heyn (1966) emphasised the variability of characters within each