Iris Josefina LISCOVSKY, María Teresa COSA & Gloria E. BARBOZA
The delimitation and relationship of several genera of Solanaceae are not resolved yet. The systematic position of Metternichia principis J.G.Mikan has long been discussed; recently it was split from Cestreae G.Don to a monotypic tribe Metternichieae Miers. The last proposal was supported mainly by the particular chromosome number of Metternichia. In addition, some pollen, anther and seed characters were used to separate Metternichia from Sessea Ruiz & Pav., the genus morphologically most closely related. An anatomical and vascular analysis of the flower was conducted to look for characters that contribute to its systematic position. The placental tissue placed in the base of the septum has never been described before in other Solanaceae species. Moreover, the process of formation of the middle petals, staminal bundles and the two vascular arcs placed on the base of the ovary, are particularities that have not been reported before in the family. The presence of two vascular arcs on the base of the ovary seems to be primitive features in the family as it happens in Humbertia madagascariensis Lam. (Convolvulaceae). The vascular characters in addition to chromosomal, pollen, anther and seed characters, postulated by other authors, support the independence of M. principis from Cestreae. Results are discussed and compared with previous reports on the family.