Trabeculae and al-accumulation in the wood cells of melastomataceae species from brazilian savanna

Family Melastomataceae is an important component of the Brazilian Cerrado flora, inhabiting different environments from those with well-drained soils to swamp soil sites. Several members of this family are recognized as aluminum (Al)-accumulating. We studied the wood anatomy of six species of Melastomataceae (Miconia albicans (Sw.) Triana, M. fallax DC., M. chamissois Naudin, M. ligustroides (DC.) Naudin, Microlepis oleaefolia (DC.) Triana, Rhynchanthera dichotoma DC.), growing in different environments of Cerrado, exploring the occurrence of trabeculae and Al-accumulation sites. We processed the material following the usual techniques in wood anatomy and histochemistry.Weused a chrome azurol-S spot-test in fresh material to detect Al-accumulation. The common features were diffuse porosity, vessel elements with simple perforation plates and vestured pits, abundant parenchyma-like fiber bands and septate fibers, axial parenchyma scanty to vasicentric, and heterocellular rays. The presence of trabeculae in vessel elements, septa in parenchyma cells, and aluminum in the G-layer of the gelatinous fiber walls, in the septa of fibers, in cambial initials and derivatives cell walls, and in the vacuole of ray cells are recorded for the first time for Melastomataceae. The results of this study indicate an additional role for gelatinous fibers in Al-accumulation, and offer a new perspective on Al-compartmentalization in the wood cells from Cerrado species.