Floral Ontogeny in Bourreria (Ehretiaceae, Boraginales)

Gynoecium and fruit ontogeny is studied in eight species of Bourreria (Ehretiaceae, Boraginales). The internal architecture of the bicarpellate ovary results from the development of several secondary septs, i.e., apical, basal, and false septs. Flower and fruit morphology provide additional characters for phylogenetic analyses. Apomorphies of monophyletic Bourreria are the valvate calyx lobes, an extensive disc, and an additional sterile chamber in each endocarpid (i.e., fruit part). The development of transfer cells and endosperm haustoria confirm the systematic placement of Bourreria in the Primarily Woody Boraginales (i.e., Heliotropiaceae, Cordiaceae, and Ehretiaceae including Lennoaceae). However, the precise systematic position of Bourreria within Ehretiaceae cannot be resolved on the basis of the morphological data provided here.