Taxonomic use of leaf anatomical characters in the genus Simarouba Aublet(Simaroubaceae)

Abstract

Summary Studies of the taxonomic value of leaf anatomical features in the neotropical genus Simarouba A ublet ( Simaroubaceae ) revealed the occurrence of four types of leaf sclereids based on their shape, ramification and arrangement within the mesophyll. These leaf sclereid characteristics seem to be not influenced by environmental conditions and are useful to distinguish from one another the three morphologically very similar continental species, S. amara , S. glauca and S. versicolor , as do the three insular species, S. berteroana , S. tulae and S. laevis . Papillate trichomes on the abaxial leaf surface occur only in the continental species and are generally a good character to separate them from the insular species; however, they may be sometimes absent or reduced and scattered in S. amara , thus precluding its taxonomic use to separate papillate and non-papillate species groups. Overlapping values for the thickness of the adaxial leaf epidermis and of the sclereid cell wall among species were found, but extreme values for these characters may help the recognition of some species.