Ceratonia siliqua

Carob (Ceratonia siliqua)
Scientific name	Ceratonia siliqua [1]
Common names	carob, St. John's bread, carob tree [2]
Genus	Ceratonia [1]
Family	Fabaceae [1]
Order	Fabales [1]
Growth form	long-lived evergreen Mediterranean tree [3]
Habitat	warm, low-elevation Mediterranean maquis and garigue [3]
Flowers	separate male and female flowers are common; hermaphroditic forms also occur; mainly insect-pollinated [2] [3]
Fruit	brown, leathery pods with sweet pulp around hard seeds [2]
Propagation	seed; budded or otherwise clonal trees are used to preserve selected traits [4]
Years to fruit	modern orchards may bear from about the fourth year after budding; timing varies with tree and site [3]

Ceratonia siliqua, commonly called carob or St. John's bread, is a long-lived evergreen tree cultivated for its sweet, edible pods. It is a warm-climate Mediterranean species associated with low-elevation maquis and garigue, and is best suited to a sunny site with freely draining soil. ^{[2] [3]}

The species is accepted as Ceratonia siliqua. ^[1] Separate male and female flowers are common, while hermaphroditic forms are also reported; orchard pollination therefore depends on the planted type and local insect activity rather than on a single species-wide rule. ^{[2] [3]}

Description

Carob is an evergreen tree with a broad, persistent canopy and a root system described as deep and extensive. It tolerates prolonged dry conditions once established, but its growth and establishment still depend on suitable drainage and protection from damaging frost. ^{[2] [4]}

Natural and cultivated trees occur in warm Mediterranean settings, including rocky or calcareous ground and heavier soils where drainage remains adequate. The species is thermophilous and frost-sensitive, so cold exposure should be judged by tree age, provenance, site and local duration of freezing rather than by a single universal temperature. ^{[2] [3]}

Cultivation

Soil and water

Choose a sunny position with good drainage. Carob is reported from rocky, gravelly, calcareous and heavier soils, but persistent saturation is unsuitable; deep or extensive roots make a freely draining profile especially important. ^{[2] [4]}

The native pattern is a warm Mediterranean climate with a pronounced dry season. Once established, carob is strongly drought adapted and can tolerate salt-laden air, but young trees should be watered during establishment and should not be left in a saturated root zone. ^[2] Mature trees can be managed in dryland systems or with supplementary drip irrigation in Mediterranean production. ^[3]

Sun and humidity

Give carob full sun and room for a large permanent canopy. Its natural lowland Mediterranean setting is warm and seasonally dry rather than persistently humid; open airflow and rapid drainage are preferable to a cramped, wet planting site. ^{[2] [3]}

Protection from frost is important for young trees and for plantings outside warm Mediterranean conditions. Salt-laden air tolerance is useful in exposed coastal sites, but it does not remove the need for adequate root-zone drainage or protection from severe cold. ^[2]

Seasonal changes

Carob's native rhythm is evergreen growth through a warm season with a dry Mediterranean period. Irrigation should be concentrated on establishment and on periods when a cultivated tree is actively growing or carrying a crop; established trees can use dryland management where soil depth and rainfall permit. ^{[2] [3]}

Flowering and pod development should be interpreted against the local warm-season pattern. In cooler marginal climates, the practical priorities are a long warm season, a frost-sheltered site and enough heat for pods to mature before the onset of damaging cold. ^[3]

Propagation

Seed is a documented propagation route, but the hard coat benefits from scarification or repeated soaking in warm water before sowing. Protected sowing and a deep container help accommodate the developing root system; keep the medium warm and well drained rather than wet. ^[4]

Seedlings do not preserve the exact sex expression or pod traits of a selected parent. Budded orchard trees are described as bearing earlier than seedlings in modern production, and clonal propagation is therefore relevant when a grower needs to preserve a selected tree's reproductive or pod characteristics. Detailed rootstock combinations and a universal grafting schedule are not established for carob. ^[3]

Flowering, fruiting, and harvest

Carob commonly has separate male and female flowers, with hermaphroditic forms also reported. Flowers are mainly insect-pollinated, and wind may also contribute in some habitats. Plant the flowering types needed for the chosen orchard design and maintain access for pollinating insects rather than assuming that every tree is self-fertile. ^{[2] [3]}

The pods develop into brown, leathery fruits containing sweet pulp around hard seeds. Harvest is timed when mature pods have darkened and detach readily; pods can be eaten or dried and milled into powder. ^{[2] [4]}

Bearing age varies with propagation and conditions. A horticultural review describes modern orchards bearing from about the fourth year after budding, but that value should not be applied unchanged to seedling trees, colder sites or every selection. ^[3]

Fruit and uses

The ripe pod has a sweet, fibrous pulp and hard seeds. Fresh or dried pods are used as food, and dried pulp is commonly processed into carob powder. The seeds are hard and are normally separated during eating or processing rather than treated as soft edible pulp. ^{[2] [4]}

Pod size, pulp proportion, sugar content and environmental adaptation are selection traits of practical interest. They vary among cultivated material, so a grower should choose a documented selection for the intended climate and processing use instead of assuming that every carob tree produces the same pod quality. ^[2]

Cultivars and selections

The selections Clifford and Santa Fe are associated with self-pollinating, hermaphroditic plants in horticultural descriptions. Those attributes are selection-specific and should not be treated as proof that all carob trees are self-fertile; orchard layout should still follow the sex expression and pollination behavior of the material being planted. ^[4]

Named carob material is also selected for pod size, pulp proportion, sugar and adaptation to local conditions. Without a cultivar-level comparison of those traits, the names should be treated as leads for choosing planting material rather than as a universal ranking of flavor, yield, climate tolerance or storage quality. ^[2]

Photos

References

• ↑ [1] GBIF species match: Ceratonia siliqua.

• ↑ [2] Carob, Ceratonia siliqua | Growables.

• ↑ [3] Tous, Romero and Batlle, The Carob Tree: Botany, Horticulture, and Genetic Resources.

• ↑ [4] Ceratonia siliqua | Plants For A Future.

Image credits

• Algarrobo, árbol frutal (Ceratonia Siliqua L., 1753).jpg — carob tree and fruit; photograph by Juan Emilio Prades Bel; CC BY-SA 4.0. Individual file page. Attribution: Juan Emilio Prades Bel / Wikimedia Commons; CC BY-SA 4.0.

• Ceratonia siliqua MHNT.BOT.2011.3.89.jpg — carob fruits and seeds; photograph by Roger Culos (user Ercé); CC BY-SA 3.0. Individual file page. Attribution: Roger Culos (user Ercé) / Wikimedia Commons; CC BY-SA 3.0.

• Ceratonia siliqua PC070978.jpg — carob tree at the Royal Botanic Gardens, Sydney; photograph by MargaretRDonald; CC BY-SA 4.0. Individual file page. Attribution: MargaretRDonald / Wikimedia Commons; CC BY-SA 4.0.