CONICET | Buscador de Institutos y Recursos Humanos

ABSTRACTThe extreme reduction of flowers in the Balanophoraceae has generated few and incomplete studies with scattered and often contradictory results with respect to embryology. Using light and scanning microscopy, gynoecium, ovule and embryo-sac development are described in two (of 4) species of Lophophytum. The pistillate flower lacks perianth, and it is reduced to one pistil formed by a superior ovary bi-loculate and two styles with capitated stigmas. Two ategmic ovules are inserted on the upper portion of a central column of placenta. The two locules are almost completely obstructed by the ovules. The term micropyle is not applicable in its usual sense, due to the absence of integuments the term "micropylar pole" instead of micropyle was used to designate the apex of the nucellus, where the megaspore mother cell develops. Vascular supply is missing in the placenta and the ovule, therefore, the calaza and the funiculus cannot be defined. In this sense was called "chalazal pole" to assign the portion where the nucellus is attached to the placenta. The embryo-sac is Adoxa type. During the migration of the two pairs of nuclei to the opposite poles, the four-nucleate embryo-sac tends to take the "J" shape. Each pair of nuclei undergoes a mitotic division to form an eight-nucleate embryo-sac. In the upper chalazal pole of the embryo-sac, a typical egg-apparatus with a central egg-cell and two adjacent synergids cells is developed. In the micropilar pole, three antipodes are formed, determining the embryo-sac inversion. The analysis of the anatomy and development of pistillate flowers and the study of the functional architecture of ovules, carpels and embryo-sac, provide embryological data of great importance to complement phylogenetic studies in the family Balanophoraceae, and even in order Santalales.