Ceratonia siliqua, commonly known as the carob tree, St John’s-bread, or locust bean (not to be confused with the African locust bean) is a species of flowering evergreen shrub or tree in the pea family, Fabaceae. It is widely cultivated for its edible pods, and as an ornamental tree in gardens. The ripe, dried pod is often ground to carob powder which is used as a substitute for cocoa powder.
The carob genus, Ceratonia, belongs to the Fabaceae (legume) family, and is believed to be an archaic remnant of a part of this family now generally considered extinct. It grows well in warm temperate and subtropical areas, and tolerates hot and humid coastal areas. As a xerophyte (drought-resistant) species, carob is well adapted to the ecological conditions of the Mediterranean region with 250 to 500?mm of rainfall per year. Carob trees can survive long drought periods but to grow fruit they need 500 to 550?mm rainfall per year. Trees prefer well-drained, sandy loams and are intolerant of waterlogging, but the deep root systems can adapt to a wide variety of soil conditions and are fairly salt-tolerant (up to 3% NaCl in soil). After irrigation with saline water in summer Carob trees could possibly also recover during rainfalls in winter. In some experiments young carob trees could uphold basical physiological functions at 40?mmol NaCl/L.