Question

Describe the various types of placentation found in flowering plants.

Answer 1

The ovule is female reproductive structure or gamete produced within the ovary. It gets fused with the male gamete transferred through pollination to the stigma of the flower. After fertilisation, it is converted into a seed.

Complete answer:
The ovary contains one or more ovules. These ovules are attached to a flat and question-like structure called the placenta. The arrangement of ovules attached to the placenta through funiculi within an ovary is called placentation.
The placentation has five types -
1. Marginal Placentation: in this type of arrangement, placenta forms a ridge on the ventral side of the ovary and the ovules are arranged in two rows attached to this ridge. It is found in the unilocular ovary. For example- Pisum sativum (pea).
2. Basal Placentation: in this type of arrangement placenta is developed the bottom or base of the ovary and it is attached to a single ovule. For example sunflower, marigold, etc.
3. Free Central Placentation: in this type of arrangement the ovules are attached to the central axis. In between ovules, no septa are present. It is found in dianthus, primrose etc.
4. Axile Placentation: in this type of arrangement the ovules attached to the central axis and these are separated by septa formed by the fusion of carpels. It is found in hibiscus, lemon, tomato, lily etc.
5. Parietal Placentation: in this type of arrangement the ovules are developed from the inner wall of the ovary attached to its periphery the ovary is one chambered it becomes two-chambered due to formation of the false septum in between the ovules.

Note:
The different arrangements of placenta help the ovule to get nutrients, necessary gases, helps in the removal of waste material and proper supply of water. In the mature fruits, the seeds are arranged in the same ways as the ovules are arranged during placentation.