Why are angiosperm anther called dithecous? Describe the structure of its microsporangium.

• The anther of androecium of angiospermic flowers are bilobed and each lobe is divided into two parts or theca. Thus, the anther of angiospermic flowers are called dithecous
• A typical microsporangium is surrounded by four layers - epidermis, endothecium, middle layer and tapetum.
• The outer 3 layers ie., epidermis, endothecium and middle layer are protective in function and help in dehiscence of anther to release pollen grains.
• Tapetum (innermost layer) nourishes the developing pollen grains and the cells of tapetum generally have more than one nucleus.
• When the anther is young, a group of compactly arranged homogenous cells called sporogenous tissue occupy the centre of each microsporangium.