Oil palm (Elaeis guineensis) is an unbranched palm, possessing a single shoot apical meristem (SAM) that may remain active for more than 100 years. Through histological analysis and 3-D reconstructions, Jouannic et al. detail the SAM structural variations that occur during the oil palm life cycle, and find that development of the SAM is characterized by a juvenile-to-mature phase transition accompanied by establishment of a zonal pattern and modified shape. SAM zonation is dynamic during the plastochron period and displays distinct features compared with other monocots.
