Wood anatomy of Schefflera and related taxa (Araliaceae). II. Systematic wood anatomy of new Caledonian Schefflera

The wood anatomy of 22 of the 26 species of Schefflera occurring in New Cal edonia was studied. Only two features (the presence of scalariform perforat ion plates and scanty paratracheal axial parenchyma) appear to be constant throughout the species examined. The pattern of wood structure diversity wa s analyzed using PCA; the results generally agree with the current recognit ion of four groups of species among New Caledonian Schefflera based on macr omorphology. Three of these groups (Dizygotheca, "Canacoschefflera" and "Ga briellae") represent natural assemblages closely related to one another. Th e fourth group (Schefflera sect. Schefflera) is isolated from the others, a s indicated by its very large rays and abundant septate fibres. The occurre nce of crystals in chambered cells of axial parenchyma was observed for the first time in Araliaceae. The wood structure of Schefflera plerandroides, previously placed in the segregate genus Octotheca, shows no essential diff erences from that of the other members of the Dizygotheca group, supporting the hypothesis that polymerous flowers have evolved independently at least twice within the Schefflera alliance.