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

A typical angiosperm is bilobed with each lobe having two theca. Hence angiosperm anther are called dithecous.
Structure of Angiosperm : It is circular and is generally surrounded by four wall layers namely,epidemise,enthothecium,middle layers and tapectum.

  1. The first three layers perform the function of protection and help indehiscence of anther to release the pollen.
    2.The innermost layer, tapectum nourishes the developing pollen grains. The cells of the tapectum possess dense cytoplasm and more than one nucleus.
  2. When the anther is young, a group of compactly arranged homogenous cells called sporogenous tissues occupies the centre of each microsporangium which produce micro spores or pollen grains.