FLORAL ONTOGENY AND MORPHOLOGY OF STIMPSONIA AND ARDISIANDRA, TWO ABERRANT GENERA OF THE PRIMULOID CLADE OF ERICALES

The flower development of a number of taxa with either unclear or only recently clarified phylogenetic positions in the order Ericales has remained uninvestigated for a long time because of the unavailability of material. Two genera, traditionally placed in the Primulaceae but often described as aberrant, are Ardisiandra, with three African species, and the monotypic East Asian Stimpsonia. We investigated the floral ontogeny of Ardisiandra wettsteinii and Stimpsonia chamaedryoides in order to improve the understanding of these species and to find support for their present position within Myrsinaceae. Stamens and petals develop from common primordia as in all primuloid taxa, but petal development is much delayed in comparison to several other Myrsinaceae s.l. Sepal initiation, common stamen-petal primordia, insertion of ovules, extensions of placental tips, and type of nectary are compared with other taxa of the primuloid clade. The identified putative synapomorphies extend the morphological basis for the discussion of the positions of these genera in the Ericales.