Floral vascular pattern of the endemic Malagasy genus Fenerivia Diels (Annonaceae)

The floral anatomy, especially the receptacle vasculature, of Fenerivia heteropetala Diels was studied. The presence of an odd calyx, reduced to a coarsely rectangular flange, is confirmed. The corolla is arranged in three whorls, i.e. the two usual ones in Annonaceae with here three outer ovate petals, and three inner linear petals, and an innermost whorl of six linear petals, not supplied by a perianth cortical vascular system as the previous whorls, and very likely evolved from a petalization of three outer stamen pairs. Moreover the androecium includes c. 200 stamens, while c. 45 apocarpous carpels comprise the gynoecium. Despite the scarcity of available material, the oddness and the symmetry shown by the floral pattern dismiss any teratological interpretation, and demonstrate that the monotypic genus Fenerivia is to be reinstated. The affinity with Polyalthia Blume s.l., which was previously suggested, appears unlikely.