Each ovary bears one or more ovules attached to a flattened, cushion-like structure called placenta.
The arrangement of ovules within the ovary is known as placentation. There are various types of placentations, namely:
a) Marginal - In marginal placentation, the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows. Example - pea.
b) Axile - When the placenta is axial and the ovules are attached to it in a multilocular ovary, the placentaion is said to be axile. Examples - china rose, tomato and lemon.
c) Parletal - In parietal 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 formation of the false septum, e.g., mustard and Argemone.
d) Free – Central - When the ovules are borne on central axis and septa are absent, the placentation is called free central. Examples - Dianthus and Primrose
e) Basal - In basal placentation, the placenta develops at thebase of ovary and a single ovule is attached to it. Examples - sunflower, marigold.
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