Draw the diagram of a microsporangium and label its wall layers. Write briefly about the wall layers ?

In a transverse section, a typical microsporangium appears near circular in outline. It is surrounded by four wall layers which are shown below :

$(A)$ Epidermis : It is the outer most protective layer. It is made up of flat cells surrounded by it. Cells are arranged tightly and their wall is thick. It helps at the time of dehiscence of anther.

$(B)$ Endothecium : It is located below the epidermis. It is radially pulled by flowers thickening at maturity. They lose water and shrink and helps in dehiscence of anther.

$(C)$ Layers of the wall : They are fibrous layer located between Endothecium and Tapetum. They are thin walled located in one to five layers. They also help in dehiscence of anther.

$(D)$ Tapetum : It is the inner most layer of layers of the wall. It has large, thin cell wall, thick cytoplasm and more then one nuclei. It is a nutrition layer. It nourishes the developing pollen grain.

In the centre of microsporangium there are compactly arranged homogenous cells which is called sporogenous tissue. The cells of sporogenous tissue undergo meiotic divisions to form microspore tetrads. This method/process is known as microsporogenesis.