In the shoots of Ceratonia siliqua, except for the hypocotyl and the first internode, a continuous superficial phellogen and complete cork cover are established only after a prolonged period of growth has elapsed. The initiation of sequent periderms is restricted to tree parts estimated to be more than 40 yr old. Microautoradiographs indicate year-round phellogen activity, which supports the idea that the carob tree is most likely tropical in origin.