Wood Anatomy of Staphyleaceae: Ecology, Statistical Correlations, and Systematics

Abstract

Summary Wood of Staphyleaceae is characterized by vessels which are mostly solitary; vessel elements are long with scalariform perforation plates (mostly more than 20 bars per plate) and with scalariform, opposite, or alternate lateral wall pitting. Imperforate tracheary elements range from fiber-tracheids with fully bordered pits somewhat less dense than those of tracheide (Euscaphis, Staphylea, Turpinia) to fiber-tracheide with reduced borders on pits (Huertea) to libriform fibers (Τapiscia) . Axial parenchyma is mostly abaxial, with tendencies towards vasicentric scanty and ray-adjacent cells and only a few diffuse cells. Rays are both multiseriate and uniseriate. Heterogeneous Type IIA. The multiseriate portion of multiseriate rays is often not sheathed with upright cells and consists of procumbent cells which often have bordered pits on radial walls. Rhomboidal crystals, tyloses, and dark-staining amorphous deposits are found in some but not all species. Quantitative features show wood of Staphylea to be less markedly mesomorphic than that of the other genera, a fact perhaps related to winter cold. The Mesomorphy index is held to be more useful in analysis of dicotyledon woods and in predicting relationship with ecology than a conductivity formula, because it runs parallel to ecological gradients, takes into account vessel element length (apparently related to embolism localization), and represents degrees of relinquishment of safety as woods become more mesomorphic. Statistical correlation among wood features of Staphyleaceae show vessel element length related to imperforate tracheary element length and to ray height because all of these are linked to fusiform cambial initial length. Correlation between vessel diameter and vessel element length is slightly weaker, as is inverse correlation between vessel diameter and vessel density (where packing constraints tend to enforce a correlation). The genera of Staphyleaceae can be easily characterized by wood anatomy features such as growth ring presence or absence, perforation plate bar number, presence of helical sculpture within vessels, type of imperforate tracheary element, presence of septa in fibers (in which case axial parenchyma is absent), ray dimensions, tylosis occurrence, and crystal presence. Wood of Staphyleaceae most closely resembles that of some Cunoniales (Saxifragales), and resembles that of Sapindales somewhat less.