“…In addition, the existing and gradually developing plant structure may exert competitive or "feed-back" effects upon the differentiating meristem (Heslop-Harrison, 1969). Such effects account for the differing specializations of each of the phytomer primordia, e.g., into fibrous secondary root or aereal adventitious root, into tiller or pistillate inflorescence, into prophyll, leaf, husk, or glume, and into male or female floret.…”