The number, position and arrangement or distribution of placentae inside an ovary is called placentation.
It is of the following types:
(i) Marginal
(ii) Parietal
(iii) Axile
(iv) Free central
(v) Basal
(vi) Apical and
(vii) Superficial
Marginal placentation: One or two alternate rows of ovules occur longitudinally along the ridge in the wall of the ovary in the area of fusion of two margins. A true placenta is believed to be absent. Ovary is unilocular. E.g. Pea, Acacia.
