Parietal Placentation in Argemone:
Parietal placentation refers to the arrangement of ovules within the ovary of a flower. In this type of placentation, the ovules are borne on the inner wall or sides of the ovary. This pattern can be observed in the genus Argemone, specifically in the species Argemone mexicana, commonly known as Mexican prickly poppy or yellow thistle.

Characteristics of Argemone:
Argemone is a genus of flowering plants in the Papaveraceae family. It is native to North and South America but can also be found in other parts of the world. Some key characteristics of Argemone include:
- Herbaceous plants or shrubs
- Leaves are alternate, lobed or prickly
- Flowers are showy, usually yellow or white
- Fruit is a capsule containing numerous small seeds

Parietal Placentation in Argemone:
The ovary in Argemone is superior, meaning it is positioned above the attachment point of other floral parts. The ovary is also unilocular, which means it has a single chamber. Within the ovary, the ovules are attached to the inner wall or sides of the ovary. This arrangement is characteristic of parietal placentation.

Advantages of Parietal Placentation:
Parietal placentation offers several advantages to the plant. These include:
- Efficient pollination: The ovules being positioned on the inner wall of the ovary allow for easier access to pollen grains during pollination.
- Increased seed production: Parietal placentation allows for a larger number of ovules to be produced within a single ovary, leading to higher seed production.
- Enhanced dispersal: The capsule fruit of Argemone splits open when mature, dispersing the numerous small seeds. Parietal placentation ensures that the seeds are evenly distributed along the inner wall of the capsule, facilitating their dispersal.

In conclusion, the parietal placentation is seen in Argemone, specifically in the species Argemone mexicana. This arrangement of ovules on the inner wall of the ovary allows for efficient pollination, increased seed production, and enhanced dispersal.