OBSOLETE cambium-like transitional zone true PO:0006067 plant_anatomy adaxial meristem (related) OBSOLETE. A cup-shaped region in the shoot apical meristem found between the central mother cell and the rib and peripheral zone. The cells of this zone are derived from the corpus intials, but in some cases they arise also from tunica initials. 形成層様移行帯 (Japanese, exact) leaf meristem (related) zona transicional semejante al cambium (Spanish, exact) ventral meristem (related) If found, this zone is a temporary feature mostly in Gymnosperms.