Placentation is the pattern or arrangement of ovules within the ovary of the flower. There are different types of placentation in the plant. They are:
Basal placentation: when the placenta is at the base of the ovary with a single ovule attached, it is known as basal placentation, eg. Sunflower, Marigold, Grasses.
Parietal placentation: when the ovary is one-chambered but due to the formation of the false septum becomes two-chambered, it is known as parietal placentation, eg. Mustard and Argemone.
Axile placentation: when the placenta is axial and the ovules are attached to it in a multilocular ovary, it is known as axile placentation, eg. China rose, Tomato and Orange.
Free central placentation: when the ovules are borne on the central axis and septa are absent, it is known as free central placentation, eg. Dianthus and Primrose.
Marginal placentation: when the placenta forms a ridge along the ventral suture of the ovary and the ovules are borne on this ridge forming two rows, it is known as marginal placentation, eg. Pea.
The grass is a prominent and omnipresent monocot flowering plant which belongs to the family Poaceae which is also known as Gramineae. The members of this family have basal placentation.
