In a typical anther, the wall layer that nourishes developing pollen grains is the

1. An anther wall has four layers: epidermis, endothecium, middle layers and tapetum. 2. The innermost tapetum surrounds the developing microspores. 3. It supplies nutrients and pollenkitt to the maturing pollen grains. _Source: Maharashtra Balbharati Std XII Biology, Ch 1 "Reproduction in Lower and Higher Plants" §1.2_