Leaf epidermal characters of Brazilian species of Solanum section Torva as taxonomic evidence

Abstract

To evaluate their taxonomic significance, the yet unknown epidermal characters of the leaves of 10 species of Solanum section Torva Nees (Solanaceae) from Brazil were determined using light and scanning electron microscopy. Our results indicated that the leaf epidermis showed epidermal cells of straight to wavy outlines. The curved pattern of anticlinal cell walls was predominant on the adaxial surface, and the wave pattern was predominant on the abaxial surface. Leaves are amphistomatic in six species ( Solanum acutilobum Dunal, Solanum bonariense L., Solanum guaraniticum A. St.-Hil., Solanum metrobotryon Dunal, Solanum scuticum M. Nee, and Solanum torvum Sw.) and hypostomatic in four species ( Solanum adspersum Witasek, Solanum paniculatum L., Solanum subumbellatum Vell., and Solanum variabile Mart.). Four different types of stomata (anisocytic, anomocytic, paracytic, and diacytic) were recognized, with the anisocytic type predominant on adaxial and abaxial surfaces. The combination of some micro-morphological characters such as density, distribution and type of stellate trichomes, the anticlinal walls of epidermal cells, and also the type and distribution of stomata proved to be the most useful and distinctive characters for the separation of species. This set of characters also may help as additional support in quality control of species having medicinal importance.