Vascularisation de la fleur pistillée de Begonia handelii

Abstract

The pistillate flower of Begonia handelii Irmscher has a tetramerous gynoecium. The analysis of serial sections shows that the anatomical pattern observed by Gauthier (1950) on trimerous gynoecia also occurs in tetramerous gynoecia. For each carpel there are theoretically seven vascular bundles which leave the stele. The vascular pattern of the pistillate flower of B. handelii leads us to adopt the appendicular theory of the inferior ovary. The position of vascular bundles, the presence of gaps, and the absence of recurrent bundles show that the ovary is formed by the union of appendicular organs. In this case, the inferior ovary results from the close union of carpels and perianth parts. In the pistillate flower of B. handelii, the perianth parts are disposed on two dimerous whorls: the first corresponds to a whorl of sepals, and the second to a whorl of petals.