Placentation refers to the arrangement of ovules within the ovary. It is of several types:  

1. Marginal placentation – Ovules are arranged along the margin of the ovary, as in peas.  

2. Axile placentation – Ovules are attached to a central axis, as in tomato and hibiscus.  

3. Parietal placentation – Ovules are attached to the inner wall of the ovary, as in mustard.  

4. Basal placentation– A single ovule is attached at the base of the ovary, as in sunflower.  

5. Free central placentation – Ovules are attached to a central column without any partitions, as in dianthus.