The pattern of attachment of an ovule to the ovary wall by the *
placenta. If there is only one ovule in the ovary then it is usually attached either at the base (
basal placentation ) or the apex (
apical placentation ). In a simple ovary the ovules may be attached either along the ventral suture (
marginal placentation ) or, rarely, all over the inner surface of the ovary wall (
laminate placentation ). In a compound ovary the ovules may be attached either on a central axis or on the wall along the junctions of the carpels (
parietal placentation ). Placentation on the central axis is termed *
axile in a multilocular ovary and *
free-central in a unilocular ovary. It is believed that free-central and parietal placentation are derived from axile placentation. The type of placentation is an important diagnostic character in many taxa.
