Placenta are soft cushion like tissues with which the ovules are attached to the inner surface of ovary wall
The arrangement of ovules within the ovary is known as placentation. The placentations are of different types i.e., marginal, axile, parietal, basal and free central
Marginal Placentation In this placentation, the plcenta forms a ridge along the ventral suture of the ovary and the ovules and the ovules are borne on this ridge forming two rows, as in pea
Axile Placentation In this placentation, the ovules are borne on central axis and the marginal of placenta grow in word and fuse, thus making a multicular ovary, as in China rose, tomato, etc
Parietal Placentation In this placentation, the ovules develop on the inner wall of the ovary or on peripheral part. Ovary is one chambered but it becomes two chambered due to the fomation of a false septum known as replam, e.g., mustard
Free Central Placentation In this type of placentation, the ovules are present on the central axis of ovary and septa is absent so ovary is unilocular, as in Dianthus and Primose.
Basal Placentation In this placentation, the placenta develops at the base of ovary and a single ovule is attached to it. as in sunflower
