Abstract

The distribution of metaxylem vessels in rattan stems is of particular interest to both physiologists and anatomists. While the former group looks at it from an angle of conduction efficiency of these climbing palms, the latter is concerned with rattan 'wood' density. The study reveals for six species of Calamus that the widest vessels are distributed in the central one third of the stem radius as vessel diameter increases from the periphery to the centre in a given internode. Along the stem length there is a small increasing trend from the base to the topthe difference between the middle and top levels is however almost negligible. The number of metaxylem vessels per unit area shows nearly the reverse trend although along-stem variation is not very consistent. Among the species the vessel diameter is positively correlated with stem size showing a stronger correlation with stem length. This supports the general view that widest vessels occur in species with longest stems