Leaf epidermal microcharacters of the Old World species of Lotus (Leguminosae: Loteae) and their systematic significance

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.