A
primordium (; plural:
primordia) in
embryology, is defined as an
organ or tissue in its earliest recognizable stage of development.
Cells of the primordium are called
primordial cells. A primordium is the simplest set of cells capable of triggering growth of the would-be organ and the initial foundation from which an organ is able to grow. In flowering plants, a floral primordia gives rise to flowering plants.