Leaf Axil Anatomy of the Araucariaceae

Abstract

Well defined, persistent meristems, which possess neither a bud-like organisation nor vascular connections with the central vascular cylinder, were found in the apparently blank leaf axils of six species of Agathis and 13 species of Araucaria. In other conifers, leaf axils of similar external appearance are usually reported to lack, or gradually lose, any specialised bud-forming tissues. Meristems were found in all axils investigated and in this respect the Araucariaceae approach the typical angiospermous condition of a bud in each leaf axil. Evidence is presented that the type of axillary meristem ontogeny previously described for A. cunninghamii may be widespread in the family.