ANATOMY OF THE FOLIAR EPIDERMIS OF THE SOLANUM NUDUM SPECIES GROUP OF SOLANUM SECT. GEMINATA (SOLANACEAE)

Solanum sect. Geminata comprises ca. 130 species of shrubs and small trees ranging from Mexico to Argentina. The species have been divided into 16 groups of which 12 are represented in Venezuela with 34 species growing in cloud forest understory, gallery and riparian forest, and disturbed areas. The Solanum nudum species group in Venezuela is composed of S. aphyodendron, S. campaniforme, S. nudum and S. tepuiense. The leaf epidermal surfaces of these species were investigated in order to discover and evaluate taxonomically useful characteristics. This represents part of the author’s ongoing study of the anatomy of the foliar epidermis in species of section Geminata in Venezuela. The following criteria were evaluated and illustrated: variations in epidermal cells; type, dimension and location of stomata; and presence, type, length, location and density of trichomes. Results show differences in some anatomical characteristics between species. The epidermal cells are variously shaped with straight or sinuous walls. Stomata are mainly anisocytic, whereas some are staurocytic. Two species are hypostomatic and the rest are amphistomatic. The trichomes are either glandular or eglandular. The glandular trichomes have a uni- or multicellular head and the eglandular ones are simple and uni- or multicellular. The significance of these variable features in relation to the other species groups of the section is discussed.