Ceratonia siliqua

carob flower


Ceratonia siliqua

L. 1753

pronounced: ser-ah-TOH-nee-uh SIL-lih-kwah

(Fabaceae — the pea family)


common names: carob, locust bean, St John's bread

Ceratonia is derived from the Greek κερατιον (keration), fruit of the carob (from κερας, a horn), referring to the seed pods; siliqua is Latin, a pod, husk. The word carob comes via Middle French from the Arabic kharrub. The ‘locusts’ eaten by John the Baptist may well have been carob seeds, hence the common name.

The carob is an evergreen tree cultivated in the Mediterranean region for its sugar-rich pods and gum-containing seeds. When growing in the wild, as it still does in eastern Mediterranean regions, it can grow into quite a large tree (up to about 15m), but cultivated trees are usually smaller. It has a broad hemispherical crown, a thick trunk with rough brown bark, and sturdy branches. There is an extensive root system, including a deep taproot.

The leaves are alternate, pinnate (there may or may not be a terminal leaflet), and 10 – 20 cm in length. The leaflets are dark green in colour, and have a very thick epidermis that contains large quantities of tannins.

Most carob trees are dioecious, but some are hermaphroditic. The trees blossom in autumn, with numerous small flowers, spirally arranged along the axis of the inflorescence in catkin-like racemes borne on spurs from old wood. Some are even borne directly on the trunk. They are pollinated by both wind and insects. The male flowers smell like human semen.

The fruit is a pod that is elongated, compressed, straight or curved, and thickened at the sutures. They are between 10 and 30 cm long, 1.5 – 3.5 cm broad, and up to 2 cm thick. They have a wrinkled surface that turns dark brown and leathery at maturation. They contain 5 – 18 hard brown seeds embedded in a sweet thick pulpy substance. Fruits take a full year to develop and ripen. They eventually fall to the ground, and are eaten by various animals, including pigs, who disperse the seeds in their droppings

The seed are remarkably similar in size, and are used as weights in eastern Mediterranean regions. the word “carat’ comes from the Arabic name of the seeds. The system was eventually standardized, and 1 carat was fixed at 0.2 gram.

The carob is a slow-growing tree, and may live for a hundred years, beginning to fruit after 6 or 7 years. It is drought-hardy, but in areas of low rainfall must be irrigated for commercial production. The trees are dew-sensitive, and can be grown only in areas where there are fewer than 220 dew nights a year. Although the trees are resistant to termites, heat and fire, they will not withstand strong winds or waterlogged conditions.

Carob products used by humans come from the dried, and sometimes roasted, pod. which is crushed to make a sort of flour. The pods are mildly sweet on their own, and are used in powdered, chip or syrup form as an ingredient in cakes and biscuits, and as a chocolate substitute. Drinks made from the crushed pods are traditionally imbibed during Ramadan.

Commercially, the most important product of the tree is locust bean gum, a thickening agent used in the food industry. It is used extensively in canned pet food to get the jellied texture.

The timber makes a very good fuel. It is also used for ornamental work or furniture making. The wood has an extremely wavy grain that makes it resistant to splitting, so it is often used as chopping blocks for splitting wood.


Photographed in a Birt Street garden in Picnic Bay, 2018
Page last updated 29th October 2018