IDIOSPERMUM AUSTRALIENSE (IDIOSPERMACEAE)—ASPECTS OF VEGETATIVE ANATOMY

Vegetative structural features of Idiospermum, a monotypic ranalean genus rediscovered in 1972, are described and contrasted with comparable features of Calycanthus and Chimonanthus (Calycanthaceae) to note resemblances and differences. The leaf trace pattern and nodal anatomy of Calycanthaceae and Idiospermaceae (one-trace and unilacunar) are very similar. The nodal anatomy of certain highly reduced leaves (scale leaves) of Idiospermum is, however, two-trace and unilacunar. The microscopic wood anatomy of Idiospermum is distinctively different in a number of respects from that of the Calycanthaceae. Although there are similarities, it is suggested that the floral anatomy and vegetative features of Idiospermum set it apart sufficiently from the Calycanthaceae to justify family rank as the Idiospermaceae.