explain different types of placentation in detail

The arrangement of ovules within the ovary is known as placentation. The different types of placentation found in plants are:

• Basal placentation: The placenta is at the base (bottom) of the ovary and a single ovule is attached to it. Example: Sunflower, marigold.
• Parietal placentation: Here ovary is one-chambered but it becomes two- chambered due to the formation of the false septum. The ovules develop on the inner wall of the ovary or on peripheral part. E.g. - mustard and Argemone.
• Axile placentation: The placenta is axial and the ovules are attached to it in a multilocular ovary. Example: China rose, tomato and orange.
• Free central placentation: The ovules are borne on central axis and septa are absent. Example - Dianthus and Primrose
• Marginal placentation: Here the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows. It is characteristic of legumes like pea.