Question

With the help of diagrams, name and describe the different types of placentation seen in angiosperms.

Answer 1

The arrangement of the ovules within the ovary in the flower is called as placentation. There are different types of placentation. They are as follows:

(i) Marginal placenta forms a ridge along the ventral suture of the ovary. The ovules are borne on this ridge forming two rows e.g., pea.

(ii) Axile placenta is axial and the ovules are attached to it in a multilocular ovary e.g., china rose, tomato, lemon.

(iii) Parietal placentation has the ovules develop on the inner wall of the ovary on the peripheral part. The ovary is one chambered. The example is mustard.

(iv) Free central placentation is when the ovules are borne on the central axis and septa absent e.g., primrose.

(v) Basal placenta develops at the base of the ovary and a single ovule is attached to it e.g., sunflower, marigold.

(vi) Superficial placentation has the ovules borne on placenta that develop all around the internal surface of the partition wall e.g., Nymphaeaceae.