Abstract

Gregory A. Dahle and Jason C. Grabosky

This paper investigates the balance between hydraulics and mechanics in tree branches by analyzing changes in the percentage of area composed of four cell types along Acer platanoides L. branches. Percent area composed of vessels members, fibers, ray parenchyma, and axial parenchyma were compared at five locations along each branch from the stem towards the branch tips. The percentage of each cell type was not found to be correlated with the angleof branch attachment to the trunk, nor the top versus bottom of each branch location. In general vessel radii decreased in the distal direction along each branch. Percent area comprised of vessels was highest in the middle of the branches and lowest at both ends, while the percent area for fibers did not differ in the secondary (radial) growth. Vessel to fiber ratios were found to vary in the same pattern as percent area vessel, which suggests that water movement is governing the balance between hydraulics and mechanics in these branches.