Wood and Bark Anatomy of Myricaceae: Relationships, Generic Definitions, and Ecological Interpretations

Wood anatomy of the single spec ies of Cana comyrica (hitherto not studied) shows that it belongs in Myricaceae, although it differs from other genera in several respects (axial parenchyma grouped in bands or columns as well as diffuse ; Heterogeneou s Type I rays; more numerous bars per perforat ion plate). The latter two features are primitive for the family . The four genera (Canacomyrica. Comptonia, Morella, and Myrica s.s .) differ from each other not onl y by qualitative features but by qu antitative features (feature means in genera mostly nonoverl apping). Wood of Comptonia and Myri ca s.s. lacks chambered crystals in axial paren chyma and ray cr ystals. Wood of Myrica S.s. has tracheids in latewood but fiber-tracheids in earl ywood. Diagnostic generic summaries are presented. Features of Myricaceae such as scalarifonn perforation plates, presence of (true) tracheids , ray types , chambered encapsulated crystals in axial parenchyma, and bark anatomy correspond with character states and expressions in Betulaceae, Casuarin aceae, Corylaceae, Juglandaceae (including Rhoipteleaceae), Ticodendrace ae and, to a lesser extent , Fagaceae and Nothofagaceae. This grouping of families can be found as Fagales in recent DNA trees . The predominance of tracheids in basal Fagales such as Myricaceae and Ticodendraceae suggests that origin of vasicentric tracheids which occur in combination with libriform fibers in Fagaceae is the product of tracheid dimorphism. Low imperforate tracheid length to vessel element length rat ios (FN ratio s) in Myricaceae are a probable indication of wood primitiveness. Quantitative vessel features of Myricace ae, as combined in Mesomorphy Ratio values , characterize wood of Myricaceae as a whole, but at the species level such values correspond to respective habitats; notably high vessel density in Comptonia may represent greater conductive safety appropriate to relatively dry habitats .