Placentation - Practice Questions & MCQ

Placentation

The arrangement of ovules within the ovary is known as placentation. It is of following types:

1. Marginal placentation: The placenta forms a ridge along the ventral suture of the ovary and ovules are borne on this ridge forming two rows. Placenta developing along the junction of the two margins of the carpel in one chambered ovary. E.g., pea, gram, etc.

2. Axile placentation: The placenta is axial and the ovules are attached to it in a multilocular ovary. The placenta develops from the central axis and the ovary is two to many chambered. For example, tomato, cotton, China rose, lily, etc.

3. Parietal placentation: The placenta develop on the inner wall of the ovary or on peripheral part. Ovary is one chambered but becomes two chambered due to false septum called replum. E.g., mustard, argemone.

4. Free central placentation: The placenta develops on the central axis and septa are absent. E.g., Dianthus, primrose, etc.

5. Basal placentation: Ovary is unilocular and the placenta develops at the base of the ovary. Ovary bears only a single ovule, e.g., wheat, maize, aster, sunflower, etc.

6. Superficial placentation: Ovary is multilocular and placenta develop all around the inner wall of the ovary. For example, water lily.