STUDIES IN THE BIGNONIACEAE. II. ONTOGENY OF DIMORPHIC ANTHER TAPETUM IN TECOMA

A developmental study of anther tapetum in Tecoma stans has shown that the hypodermal archesporial layer differentiates in each microsporangium by cutting off a primary parietal layer to the outside (epidermal) and a primary sporogenous layer to the inside (connective). The primary parietal layer divides periclinally, producing the outer secondary parietal layer, which by further divisions, forms the future endothecium and the middle layer. On epidermal side, the inner secondary parietal layer gives rise to tapetum. The remainder of the tapetum on the inside (connective) is contributed by the parenchymatous connective cells lying just outside the sporogenous cells. The tapetum thus follows the dicotyledonous type of ontogeny. It also shows a distinct dual origin and is structurally dimorphic.