Androecium

 Androecium is the third essential whorl which consists of stamens or male reproductive part of a flower. Each stamen is composed of a slender stalk like filament supporting a knob like structure called anther. Each anther usually consists of two anther lobes connected with the of a connective.

Forms of fused androecium:

1. Adelphous: The stamens are fused by their filaments but the anthers are free.

1. If the filaments of all the stamens fused to form one groups, is termed as monoadelphous e.g. Hibisus rosa sinensis.
2. When they are fused in two groups called  diadelphous.
3. Some time fused in more than two groups and described as polyadelphous e.g. Citrus.

2. Syngenesious or Synantherous: In this case the filaments of stamens are free and anthers are fused by their sides to form a ring around the style e.g. Sumflower.
3. Synandrous: When both filaments and anthers of the stamens are fused completely e.g.Cucurbita.