Systematic and ecological wood anatomy of N eotropical S chefflera ( A raliaceae), with an emphasis on the D idymopanax group

Wood anatomy has been investigated from 35 species belonging to the N eotropical clade of the polyphyletic genus S chefflera ( A raliaceae), representing three of the five subgroups ( D idymopanax , C repinella and S ciodaphyllum ). The species examined are rather uniform in their wood structure, sharing the presence of scalariform and simple perforation plates, septate fibres and scanty paratracheal axial parenchyma. The observed variation in many wood characters showed statistically significant differences relative to latitude, climate and, especially, vegetation types. In particular, the intervessel pits are larger in species from higher latitudes and in seasonally dry habitats than those from lower latitudes and rainforests. Latitudinal and ecological trends in the variation of vessel element lengths, bar numbers on perforation plates, intervessel pit sizes and ray widths may be at least partially explained as effects of adaptation to drier environments in the course of dispersal outside the A mazonian region and diversification in the A tlantic F orest subclade and the S avannic subclade within the D idymopanax group. The occurrence of a granular annulus on the intervessel pit membranes in S . chimantensis and S . sprucei (both of the C repinella group) is the first record of this feature in A raliaceae. In comparisons of N eotropical S chefflera with the other major clades of S chefflera sensu lato , wood anatomical diversity is consistent with the polyphyly of this genus based on molecular phylogenetic analyses. © 2013 The Linnean Society of London, Botanical Journal of the Linnean Society , 2013, 173 , 452–475.