Wollemi Pine (Wollemia nobilis, Araucariaceae) Possesses the Same Unusual Leaf Axil Anatomy as the other Investigated Members of the Family

Abstract

Most leaf axils of most conifers are devoid of any bud-forming potential. Bycontrast, the numerous, apparently blank, leaf axils of the previouslyinvestigated species of the Araucariaceae possess unusual, if not unique,little-differentiated axillary meristems which have neither a bud-likeorganisation nor vascular or provascular connections with the central vascularcylinder. These meristems are exogenous in origin but are buried beneath thestem surface by the formation of localised periderms. Leaf axils fromplagiotropic branch shoots of juvenile and adult morphology and fromorthotropic leaders of adult morphology of the recently described Wollemi pine(Wollemia nobilis W.G.Jones, K.D.Hill & J.M.Allen)have been found to possess a anatomy similar to that previously described forthe Araucariaceae. Thus, W. nobilis is, on the basis ofits leaf axil anatomy, a typical member of the Araucariaceae.