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Webster 1913 Edition

Noun.

(Anat.)

The mode of formation of the placenta in different animals;

as, the

placentation

of mammals

(Bot.)

The mode in which the placenta is arranged or composed;

as, axile

placentation

; parietal

placentation

Noun.

In botany, the disposition of the cotyledons or lobes in the vegetation or germination of seeds.

placentation ‎(countable and uncountable, plural placentations)

(biology) the local fusion of the embryonic stage of an animal to its parent for physiological exchange to promote the growth and development of the young; involves a placenta in non-egglaying mammals