Ceratonia is a flowering tree native to the Mediterranean regions of Europe. The scientific name is Seratonia siliqua, commonly known as the carob tree. The long, bean-shaped pods are used to make carob, a sweet substance often used as a substitute for chocolate. Ceratonia is in the plant family Leguminosae, a large family that includes common legumes such as beans and peas. The carob tree is further classified in the subfamily Caesalpinioideae, comprised mostly of trees that grow in tropical and sub-tropical regions.
A mature ceratonia tree grows from about 50 feet to 55 feet (about 15 m to 17 m) tall and is in leaf year round. The flowers bloom in mid- to late summer in clusters of tiny red blossoms. Individual trees are either male or female and both are needed for pollination to occur. When cultivated commercially, one male tree is planted for every 25 female trees.
The Mediterranean climate, with its hot, dry summers and cool, wet winters offers preferred conditions for the ceratonia tree. While ideal, a Mediterranean climate is not required; temperatures as low as 20 degrees Fahrenheit (about -6 C) will not harm mature trees, though saplings are frost sensitive. While cold tolerance is limited, the carob tree can withstand hot summers when temperatures climb as high as 104 degrees Fahrenheit (40 C).
Accustomed to the long, dry summers of the Mediterranean climate, a mature ceratonia can survive periods of drought. Ideally, a mature, cultivated carob tree should receive about 30 inches (about 76 cm) of water a year, though the tree will thrive with as little as 6 inches (15 cm). In cool, damp climates, water will only be necessary during the hottest months of the summer. The ceratonia tree is tolerant of salty air, a growing condition that is less limiting than that of many plants that are sensitive to maritime climates.
Deep, loamy soil with good drainage provides the ideal growing conditions for a ceratonia tree. Rocky soil is suitable and preferable to wet, heavy, or clay-like soil. Alkaline soil with a pH range of 6.2 to 8.6 is preferable, while acidic soils are unsuitable.
The seed pods are about 12 inches (30 cm) long, fibrous, and contain a row of seeds in a pattern similar to that of a bean or pea plant. The seedpods and seeds are naturally sweet. Ground seedpods are used to make carob. The seeds and seedpods are also used in moderation for livestock feed and as a traditional cure for stomach ailments.