Traditional classifications have placed Elaeocarpaceae and Tremandraceae into different orders, even into different subclasses of eudicots. Molecular studies, however, have proposed a profound rearrangement of families resulting in a new order, Oxalidales, comprising widely disparate families, including Elaeocarpaceae and Tremandracae, in addition to Oxalidaceae, Connaraceae, Cephalotaceae, Cunoniaceae, and Brunelliaceae (APG, 1998; Savolainen et al., 2000). Furthermore, more detailed molecular studies have even found Tremandraceae to be seemingly nested in Elaeocarpaceae (Savolainen et al., 2000; Soltis et al., 2000). As part of a larger study, which focuses on a comparison of the morphology, anatomy and histology of flowers of all families of Oxalidales, special attention was given to assessment of the inclusion of Tremandraceae (3 genera, endemic to Australia) into Elaeocarpaceae (9 genera, pantropical and temperate). A number of potential synapomorphies shared by all, or part of Oxalidales were found. In addition, characters shared by the Elaeocarpaceae/Tremandraceae clade alone are also present. These characters include: petals larger than sepals in bud and forming the protective organs, petals induplicate-valvate with involute margins, anthers elongate and basifixed with lignified hairs, anther dehiscence poricidal, ovary locules with lignified hairs, ovules with a chalazal appendage, ovules with hairs, and petals with three vascular traces (although they have a narrow base). Thus it appears that floral structural studies support the molecular findings: the placement in Oxalidales, and the close relationship of Tremandraceae and Elaeocarpaceae.

Key words: Elaeocarpaceae, eudicots, floral structure, Oxalidales, Tremandraceae