The impact of receptacular growth on polyandry in the Myrtales

RONSE DECRAENE, L.-P. & SMETS, E., 1991. The impact of receptacular growth on polyandry in the Myrtales. The androecium of the Myrtales shows a wide variation in structure and development, linked with an original diplostemony. The difference between a centrifugal stamen inception in Lythraceae against a centripetal inception in other families has been a major issue in discussing the internal relationships of the Myrtales. The first stamens usually arise as pairs opposite the petals on primary androecial primordia. It is shown that the number of stamens that are initiated and the difference between the direction of development of more stamens are based on the extent of growth of the receptacle after the inception of the primary androecial primordia. In Lagerstroemia indica , receptacular growth takes place between stamens and petals providing room for a centrifugal development. In the Punicaceae and Myrtaceae growth of the receptacle occurs between the androecium and gynoecium, leading to a centripetal development of the stamens. The development of a ring-wall is discussed and a comparison is made with other types of complex polyandry.