Wood Anatomy of the Altingiaceae and Hamamelidaceae

Abstract

Wood anatomical data for all three extant genera of the Altingiaceae and 23 of the 27 extant genera of the Hamamelidaceae were compiled in an effort to find features distinctive to genera, tribes, or subfamilies within these families. All genera studied have diffuse porous wood (except Corylopsis which tends to be semi-ring porous), vessels are predominantly solitary and narrow (<100 μm, usually <50 μm) and angular in outline, vessel elements are long (>800 μm) with scalariform perforation plates with average bar numbers of 9–44, intervessel pits are mainly scalariform to opposite, vessel-ray parenchyma pits are scalariform with slightly reduced borders and usually are in the square to upright marginal ray parenchyma cells, rays are heterocellular and narrow, usually 1–3-seriate. Although the wood anatomy of both families is relatively homogeneous, it is possible to key out many genera using a combination of qualitative (presence/absence and location of helical thickenings in vessel elements and fibers, crystal occurrence, axial parenchyma abundance, degree of ray heterogeneity) and quantitative features (number of bars per perforation plate and ray width). Helical thickenings are present throughout the vessel elements in three genera (Loropetalum, Altingia, Semiliquidambar) and are restricted to the vessel element tails in two genera (Corylopsis, Liquidambar). Loropetalum has helical thickenings in ground tissue fibers as well. Axial parenchyma abundance varies from scarce to relatively abundant diffuse to diffuse-in-aggregates. One clade of the tribe Fothergilleae (Distylium, Distyliopsis, Sycopsis, Shaniodendron, Parrotia, Parrotiopsis) has more abundant axial parenchyma and is characterized by narrow, usually interrupted bands of apotracheal parenchyma. Nearly exclusively uniseriate rays occur in some species of Hamamelis and in Exbucklandia, Chunia, Dicoryphe, and Fothergilla. These data on extant Altingiaceae and Hamamelidaceae not only provide information relevant for systematic, phylogenetic and ecological wood anatomy and wood identification, but also give context for reviewing the fossil woods assigned to them. A new combination is proposed for the Miocene Liquidambar hisauchii (Watari) Suzuki & Watari from Japan: Altingia hisauchii (Watari) Wheeler, Baas & Lee.