Ceratonia siliqua

The carob (Ceratonia siliqua) is a flowering evergreen tree or shrub in the legume family, Fabaceae. It is widely cultivated for its edible pods, and as an ornamental tree in gardens and landscapes. The carob tree is native to the Mediterranean region and the Middle East.

In the Mediterranean, carob pods are often used as animal feed and in times of famine, as "the last source of [human food in hard times". The ripe, dried, and sometimes toasted pod is often ground into carob powder, which is sometimes used as an ersatz cocoa powder, especially in the 1970s natural food movement. Carob bars (an alternative to chocolate bars), as well as carob chips (an alternative to chocolate chips), and carob treats are still often available in health food stores. Carob pods are somewhat sweet, not bitter, and contain no theobromine or caffeine.

The word "carob" comes from Middle French carobe (modern French caroube), which borrowed it from Arabic (kharrob, "locust bean pod"), ultimately perhaps from Akkadian language kharubu or Aramaic kharubha, related to Hebrew harubh. Ceratonia siliqua, the scientific name of the carob tree, derives from the Greek "fruit of the carob", and Latin siliqua "pod, carob".

In English, it is also known as "St John's bread", as well as "locust tree", (not African locust bean) the designation also applied to several other trees from the same family.

The unit "carat", used for weighing precious metal and stones as alluding to an ancient practice of weighing gold and gemstones against the seeds of the carob tree by people in the Middle East. The system was eventually standardized, and one carat was fixed at 0.2 gram.

In late Roman times, the pure gold coin known as the solidus weighed 24 carob seeds (about 4.5 grams). As a result, the carat also became a measure of purity for gold. Thus, 24-carat gold means 100% pure, 12-carat gold means the alloy contains 50% gold.