Floral Ontogeny of Oleaceae and Its Systematic Implications

Although the floral morphology of Oleaceae appears to be simple at first sight, fundamental problems still exist. The most detailed morphological studies date back to the 1920s but do not contain developmental data. Such data, based on the SEM investigation of 15 species out of 10 genera and covering most tribes and subtribes of the family, are presented here. In the dominant floral type, the perianth is tetramerous. The four sepals initiate simultaneously in orthogonal positions on the floral apex. The corolla partly emerges as a continuous ringlike structure from which four petal lobes arise in diagonal positions (early sympetaly). In other cases, the petal primordia emerge separately, fusing later to a corolla tube (late sympetaly). The primordia of the two stamens arise in transverse positions. The gynoecium is bicarpellate throughout the family, with the two carpel primordia emerging in median positions. Deviations from the common pattern are represented in Nyctanthes and Jasminum (as well as in Meno...