placenta

noun

(L. placenta: [flat] cake) (pl. placentae) The part of the ovary wall (a ridge of tissue) in flowering plants, to which the ovules arise and are attached. The arrangement of ovules on the placenta (placentation) is variable, depending on the number of carpels and whether they are free (see apocarpy) or fused (see syncarpy). In ferns and related plants, the tissue giving rise to sporangia.