Sebastiania commersoniana is a very common tree species in alluvial environments with diverse soil conditions due to its plasticity and ability to tolerate periods of flooding. In this study we sampled 21 adult individuals of this species on the Iguaçu River plain, for wood anatomy characterization and interpretation using a functional approach. S. commersoniana has diffuse porous, solitary vessels and multiples of two to six, radially arranged with simple perforation plates; low vessel frequency (12-16-20/mm²), with diameter of 54-88-117 µm, and vessel elements 164-602-1025 µm in length. The fibers are 656-1222-2050 µm in length, 10-26-42 µm wide, the walls are 1.0-2.8-5.1 µm thick. Fibers with a gelatinous layer are common. Apotracheal parenchyma diffusein-aggregates is found, while paratracheal parenchyma is scanty. Rays are uniseriate, 164-805-2787 µm tall and 12-22-35 µm wide. Perforated ray cells are frequent, as well as scar tissue containing starch grains. Starch also occurs in the radial and axial parenchyma. This species develops tension-wood in inclined trees. Most of the features observed coincide with available descriptions of the genus and family to which the species belongs. Some qualitative features are discussed on the base of possible roles and implications for species autoecology.
alluvial forest; ecological anatomy; riparian forest; secondary xylem
