The stamens are modified leaves or microsporophylls concerned with the production of microspores or pollen grains. There are two part of stamen - the long and cylindrical filament and the terminal bilobed structure called the anther. The proximal end of the filament is attached to the thalamus or the petal of the flower.Each lobe of anther has two pollen sac or microsporangia. Such as anther is called dithecous. In certain families (e.g. Malvaceae), the anther is monothecous.
The bilobed nature of an anther is very distinct in the transverse section of an anther. The anther is a four sided or tetragonal structure consisting of four microsporangia located at the corners, two in each lobe.
The microsporangia develop further and become pollen sac. They extended longitudinally all through the length of an anther and are packed with pollen grains.
STRUCTURE OF ANTHER
— Anther has two lobes (bilobed). Each lobe consists of two theca. Hence it is dithecous.
— Anther is a tetragonal structure which consist of four microsporangia located two in each lobe.
— Microsporangium develops into pollen sacs.
— Pollen sacs run longitudinally and contain pollen grains.