The ontogeny of the tapetum and parietal layers, as well as the stomium development and the dehiscence of the anther of Tabebuia pulcherima was studied. The anther wall formation follows the Dicotyledoneous type. The primary parietal layer, the sporogenous tissue, and the inner tapetum are differentiated directly from the ground meristem. The sporogenous tissue, as seeing in a transverse section, is organized in one cellular strip with a horseshoe outline. The tapetum is secretory and shows a distinct dual origin. The inner tapetai layer differentiates earlier than the outher. The two tapetai layers are moderately dimorphic. However, even such a dimorphism is lost at the end of the sporangium meiosis. The tapetai dimorphism and the precocious differentiation of the inner tapetum was interpreted as expression of a developmental gap between the two layers. At the four corners of the anther, a multilayered endothecium with annular or spiral fibrous thickenings in their cell walls is formed. The deiscence is preceded by the placentoid tissues degeneration and the rupture of the interesporangial septa. Only the epidermal cell rows, at the two sides of the stomial dehiscing place, are involved in the stomium rupturing.
Bignoniaceae; Tabebuia; tapetum; dehiscence; ontogeny