Mericloning is the vegetative culture of a plant through the tissue culture of apical meristems that began in the 1960s. Plants produced through this process are relatively identical. Meristemic cells are undifferentiated cells that occur in areas of new growth. They are analogous to human stem cells. Shoot apical meristems are usually used but root apical meristem can also be used. When orchids are cultured through mericloning, they produce a mass of protocorms which can develop into plants.