MORPHOLOGY OF FOLIAR EPIDERMIS IN TWO GROUPS OF SOLANUM SECTION GEMINATA (SOLANACEAE)

Solanum arboreum, S. falconense, S. gratum, S. lucens, S. ripense and S. tanysepalum of the S. arboreum group; S. imberbe and S. sieberi of Solanum deflexiflorum group were studied in the context of ongoing anatomical research in the Geminata section of the genus Solanum, in order to identity epidermal features that can be recognized and employed as useful taxonomic characters. Leaf materials were taken from herbarium specimens and treated using conventional anatomical procedures. Qualitative features such as epidermal cell wall shape and thickeness; stomata distribution, type and density, and trichome type and distribution were evaluated as well as quantitative traits such as stomatal length and width, stomatal index (SI) and trichome density. Some of the studied epidermal features are of particular interest, especially on the adaxial surface, because they differ conspicuously between species. Polygonal cells are unique in all studied species but S. lucens and S. tanysepalum. Differences were also found in trichome, distribution (on intercostal areas of S. imberbe and S. sieberi) as well as trichome type, which preved useful in differentiating some of the studied species. Glandular long and short, branched trichomes were found only on the adaxial epidermis in S. tanysepalum. On the abaxial surface only S. falconense showed eglandular, long and unbranched trichomes. A key for identification of the species is provided.