Premise of research:
This study tackles the general question of whether the assessment of leaf anatomical characters has potential utility in characterizing clades and taxa at various levels of the taxonomic hierarchy of the Primulaceae.
Fully expanded field-collected leaves of 33 species from five genera were sampled. The material was subjected to anatomical procedures by LM, SEM, confocal microscopy, and epifluorescence microscopy. Principal component analyses were performed to test the validity of leaf anatomical features as a method of separating the species and genera. In addition, to understand character evolution, some leaf anatomical characters were plotted on a DNA phylogeny.
The basic leaf anatomical structure was shared by all species: dorsiventral mesophyll, singlelayered epidermis, and mesophyll cells containing druses. In contrast, other attributes, such as trichome types, stomata, and cuticular ornamentation, display diversity, which is helpful in defining groups within the Neotropical Primulaceae. In addition, several apomorphies for genera and subfamilies could be identified. The subfamily Myrsinoideae can be characterized by its secretory cavities and ducts. The only representative of the Theophrastoideae we studied stood out by its extraxylary fiber bundles. Cybianthus can be segregated from other genera by its paracytic stomata, Myrsine by the presence of an additional bundle above the vascular system in the midrib, Stylogyne and Ardisia by the weakly dorsiventral mesophyll, and Jacquinia by the presence of bundles of extraxylary fibers in the mesophyll and marginal sclerenchyma.
On the basis of multivariate analysis, it was possible to validate the efficacy of leaf anatomical characters in species and genus segregation, and on the basis of these results, it is further possible to use such data as the basis for future taxonomic delimitation.