Septal nectaries are formed by local regions of later nectariferous epidermal cells on the sides of the carpels at their very base. In order that the epidermal cells may differentiate into nectariferous cells, the carpels which constitute the gynoecium have to develop as separate organs. It was argued that if no septal nectaries develop, this free carpel development does not take place. The nectariferous regions get shaped as nectar containers by dermal fusion of the sides of the carpels surrounding them, by upward growth of the apex, and mostly also by meristematic continuity of part of the ovary wall on the outside. By the latter the level of the openings of the nectaries on the ovary is defined. Septal nectaries in Monocotyledons are considered original.