The ovules are attached on ovary walls on one or more cushion called placenta. The manner in which placenta are arranged on ovary wall is known as placentation.
Basal placentation : The placenta develops at the base of ovary and a single ovule is attached to it, as in sunflower, poaceae etc.
Axial placentation: The ovules are attached to it in a multilocular ovary, the placentation is said to be axile, as in china rose, tomato and lemon.
Parietal placentation: The ovules develop on the inner wall of the ovary or on peripheral part. Ovary is onechambered but it becomes two chambered due to the formation of the false septum, e.g., mustard and Argemone etc.
Free central placentation: When the ovules are borne on central axis and septa are absent, as in Dianthus and Primrose etc.