The taxonomic value of leaf anatomy for species Byrsonima: a difficult genus of Malpighiaceae Juss.

ABSTRACT We studied the leaf anatomy of 15 species of Byrsonima and a single species of Diacidia as an outgroup to test the relevance of leaf anatomical characters to the complicated taxonomy of this genus. We present complete anatomical descriptions for petioles and leaf blades, together with an anatomical matrix, dendrogram and an identification key for the studied taxa. The most informative characters were the presence of stomatal crest, trichome type, epidermis type, contour and conformation of the vascular system in the diaphragm and medium petiole and number of accessory bundles. The aforementioned characters revealed that the anatomy of the petioles in the genus differs from that of petioles in the outgroup taxon with regard to vascular system conformation and the absence of cortical sclereids. Furthermore, the anatomy of the leaf blade appears to be quite informative in Byrsonima, especially in synonymized species. The anatomical features evaluated here have great value for Byrsonima taxonomy. These features may be used in an evolutionary approach to the group, especially for proposing a new classification system based on morphoanatomical characters of the genus.