In the developmental anatomy of flowering plants, the archesporium is the group of initial cells that differentiate within the sporangium. In an anther (microsporangium), these cells divide to form an outer primary parietal layer and an inner primary sporogenous layer. The parietal layer further divides to produce the wall layers—endothecium, middle layers, and tapetum—while the sporogenous layer gives rise to the sporogenous tissue/cells .