In marginal placentation, one or two alternative rows of ovules appear longitudinally along the ridge in the wall of the ovary at the area of fusion of its two margins or ventral suture.
A true placenta is absent in marginal placentation.
The ovary in marginal placentation is unilocular.
Example of marginal placentation:
Marginal placentation is found in Acacia which belongs to the family Leguminosae.