WOOD AND BARK ANATOMY OF TICODENDRON - COMMENTS ON RELATIONSHIPS

The single known species of Ticodendron has notably primitive wood (scalariform perforation plates with numerous bars; primary wall remnants in perforations; scalariform lateral wall pitting in vessels; imperforate tracheary elements all tracheids; axial parenchyma diffuse; rays Heterogeneous Type I). Although wood of Betulacease and Corylacease (Betulacea subfamily Coryleae of most authors) is more specialized, primarily in tracheary element morphology and ray histology, wood features in these families are consonant with relationship to Ticodendron. Presence of crystals in rays is alike in Ticodendron, Corylacease, and Fagacease. Bark anatomy features are shared by the fagalean families: fusiform-shaped nests of sclereids containing large rhomboidal crystals; druses in cortex, phloem parenchyma, and ray parencyma; and subdivision of ray cells that contain druses. Placement of Ticodendron in Fagales as a separate family, more primitive than others in the order, is indicated by the data reviewed.