Systematic leaf anatomy of Baccaurea, Distichirhops, and Nothobaccaurea (Euphorbiaceae)

The leaf anatomical diversity of the genera Baccaurea Lour. (43 species), Distichirhops Haegens (3 species) and Nothobaccaurea Haegens (2 species) (Euphorbiaceae) is described. Two species of Aporosa and three species of Maesobotrya were examined for comparison. The following characters are important for the delimitation of species: hair types, the position of the glandular areas on the leaf margin, the hairiness and size of the glandular areas, the number of epidermal layers, the presence of (mucilage) idioblasts in the epidermis, the presence of palisade parenchyma above the vascular bundles, and the birefringence of the spongy parenchyma cell walls. However, leaf anatomy did not yield characters for distinction between the five genera studied. Phenetic analysis resulted in a grouping based on leaf anatomical similarities that corresponds to a large extent with the phylogenetic position of species based on a cladistic analysis of largely macromorphological features (Haegens, 2000).