Organs of a flower are initiated in the acropetal sequence

The floral apical meristem of buttercup

A median longitudinal section through the floral meristem of buttercup (Ranunculus sp.) at the stage of the initiation of pistils. Flowers of buttercup contain numerous stamens and pistils arranged in a spiral manner. In the perianth, only portions of petals are shown which are at an advanced stage of their development. In accordance with the numerous stamens and pistils, the receptacle is unusually elongated.

Organs of a flower are initiated as the cylindrical protrusions at the periphery of the floral apical meristem.