Ceratonia siliqua

Ceratonia siliqua is an evergreen tree reaching 15 m tall at medium growth rate. Hardy to UK zone 8 and frost tender, it remains in leaf year-round and flowers August to October. The dioecious plant is pollinated by wasps and flies and fixes nitrogen. It grows in light sandy or medium loamy well-drained soils, tolerates very alkaline pH, requires full sun, and withstands drought and strong winds though not maritime exposure.

Description

An evergreen tree. It grows 12-15 m tall. It spread to 4 m across. It has a dark green round crown of compound leaves. These almost hide the trunk. The trunk is short, erect and thick. The leaves are leathery. The tree flowers in autumn. Male and female flowers are on separate trees. They grow in flower clusters on the previous year's growth. The flowers are small and red. The pods develop in spring. The flat pods are 30 cm long and 2.5 cm wide. They are thick, brown rough and leathery. The seed are constant in size and were used for the carat weight (200 mg). There are several cultivated varieties.

Edible Uses

Seedpods can be eaten raw or ground into a powder. They are filled with a sweet, saccharine pulp that can be eaten green or dried. Though very sweet, the pulp is fibrous; it is used as a chocolate substitute in cakes and drinks and is rich in sugars and protein. The pods contain approximately 55% sugars, 10% protein, and 6% fat. The seeds are rich in protein; a flour made from them is approximately 60% protein, free from sugar and starch, suitable for baking, and can also serve as a chocolate substitute. An edible gum extracted from the seed acts as a substitute for Gum Tragacanth, functioning as a stabilizer, thickening agent, and egg substitute. Roasted seeds can be used as a coffee substitute.

Traditional Uses

The seed pods can be eaten green or dried. They are sweet. The pulp can be used as a chocolate substitute. They are used for jam. The seed can be ground to make flour. An edible gum can be extracted from the seed. It is a thickening agent and egg substitute. The roasted seed is a coffee substitute. The leaves can be used as a green vegetable. Caution: The leaves are probably purgative. Caution: The pods contain tannin and can be toxic in large amounts.

Medicinal Uses

The pulp in the seedpods is nutritious, sweet-tasting due to its high sugar content, and mildly laxative. Used in decoction, the same pulp is astringent and treats diarrhoea while gently cleansing and relieving irritation in the gut. The seedpods are also used in treating coughs. A flour made from ripe seedpods is demulcent and emollient and is used in the treatment of diarrhoea. The seed husks are astringent and purgative. The bark is strongly astringent, and a decoction of it is used to treat diarrhoea.

Distribution

It is a subtropical plant. It is native to Arabia. It suits warm temperate zones. It tends to grow in rocky places near the sea shore. It needs a well drained moderately fertile soil. It does well on calcareous soils. It can grow in alkaline soils. It is commonly seen on deep chalky soils where the limestone is cracked. It is very drought resistant. It suits hot and semi-arid regions. It grows in areas with an annual rainfall between 310-4,030 mm. It can tolerate some salt spray. The deep roots find moisture. It is frost tender. Symbiotic relationships with soil bacteria enable it to fix nitrogen. It can grow in arid places. It does not fruit well in high rainfall areas. It grows in Miombo woodland in Africa. In Brisbane Botanical Gardens. It suits hardiness zones 8-11.

Where It Grows

Africa, Albania, Algeria, Angola, Arabia, Argentina, Asia, Australia, Balkans, Britain, Bulgaria, Canada, Canary Islands, Cape Verde, Caribbean, Caucasus, Central Africa, Chad, China, Colombia, Comoros, Crete, Croatia, Cyprus, East Africa, Egypt, Ethiopia, Europe, Fiji, France, Gibraltar, Greece, Hawaii, India, Indonesia, Iran, Iraq, Israel, Italy, Jordan, Kenya, Lebanon, Libya, Malawi, Malta, Marquesas, Mauritius, Mediterranean*, Mexico, Middle East, Monaco, Morocco, Mozambique, Namibia, New Zealand, North Africa, North America, Pacific, Pakistan, Palestine, Peru, Portugal, Reunion, Russia, Saudi Arabia, SE Asia, Serbia, Sicily, Sinai, Slovenia, Somalia, South Africa, Southern Africa, South America, Spain, Sudan, Syria, Tasmania, Tanzania, Trinidad-Tobago, Tunisia, Turkey, Türkiye, Uganda, USA, Yemen, Yugoslavia, Zambia, Zimbabwe,

Cultivation

Requires a very sunny position in any well-drained moderately fertile soil. Does well in calcareous, gravelly or rocky soils. Tolerates salt laden air. Tolerates a pH in the range 6.2 to 8.6. The tree is very drought resistant, thriving even under arid conditions, the roots penetrating deep into the soil to find moisture. This species is not very hardy in Britain but it succeeds outdoors in favoured areas of S. Cornwall, tolerating temperatures down to about -5°c when in a suitable position. The young growth in spring, even on mature plants, is frost-tender and so it is best to grow the plants in a position sheltered from the early morning sun. The carob is frequently cultivated in warm temperate zones for its edible seed and seed pods. Mature trees in a suitable environment can yield up to 400 kilos of seedpods annually. There are named varieties with thicker pods. Seeds are unlikely to be produced in Britain since the tree is so near (if not beyond) the limits of its cultivation. The seed is very uniform in size and weight, it was the original 'carat' weight of jewellers. This species has a symbiotic relationship with certain soil bacteria, these bacteria form nodules on the roots and fix atmospheric nitrogen. Some of this nitrogen is utilized by the growing plant but some can also be used by other plants growing nearby. Pods are typically harvested in Autumn. It flowers in Spring. Carob grows at a moderate pace, reaching maturity in about 5-6 years.

Propagation

Pre-soak seed for 24 hours in warm water before sowing; if it has not swollen, repeat soaking until it does. Sow in a greenhouse in April. Germination should occur within two months. Prick seedlings out into individual deep pots as soon as they are large enough to handle, and grow them on in a greenhouse for at least their first winter. Plant out into permanent positions in late spring or early summer after the last expected frosts, and provide cold protection for their first few winters outdoors.

Other Uses

Carob is used as a shade tree and for erosion control; its pods can serve as animal feed and the tree can improve soil fertility. A flour made from the seedpods is used in the cosmetic industry to make face-packs. Tannin is obtained from the bark. The flowers are rich in nectar and pollen, attracting pollinators including bees. The pods provide food for wildlife, particularly mammals and some birds, and the tree's dense foliage offers shelter and nesting opportunities for birds and small animals. Leaf litter contributes habitat for insects and other organisms. The rough bark and accumulated leaf litter provide overwintering and shelter sites for invertebrates. The wood is hard and lustrous; it is highly valued by turners and is also used for marquetry and walking sticks.

Production

It is very slow growing. Mature trees can yield 400 kg of seedpod per year. Fruit are produced after 10-12 years when grown from seed. Trees bear fruit in the fifth or sixth year after grafting. Trees can remain productive for 80-100 years. Pods are usually shaken off the tree. They are sun dried for 1-2 days.

Other Information

It is a cultivated food crop.

Notes

Biblical references Luke 15:16. There is only one (2) Ceratonia species. Chemical composition: Protein (crude) = 6.1% (dry). Fat = 2.6% (dry). Fibre (crude) = 2.2% (dry). Ash (insoluble) = 5.1% (dry). Carbohydrate (insoluble): Starch = 1.4% (dry). Sucrose = 0.8% (dry). D-glucose = 0.4% (dry). D-fructose = 0.2% (dry). Amino acids (g [16g N]-1): Aspartic acid = 5.9g. Threonine = 2.5g. Serine = 3.0g. Glutamic acid = 7.8g. Proline = 11.6g. Glycine = 7.4g. Alanine = 3.3g. Cysteine = 1.0g. Methionine = 0.7g. Isoleucine = 2.2g. Leucine = 3.8g. Tyrosine = 2.3g. Phenylalanine = 2.5g. Lysine = 3.0g. Histidine = 1.7g. Arginine = 4.3g. Minerals: Sulphur = 0.10% (dry). Potassium = 0 .09% (dry). Magnesium = 0.09% (dry). Calcium = 0.23% (dry). Na = 0.01% (dry). K = 1.48% (dry). Zinc = 17 mg/kg-1 (dry). Iron = 203 mg/kg -1 (dry). Manganese = 16 mg/kg-1 (dry). Copper = 7 mg/kg-1 (dry). Aluminium = 128 mg/kg-1 (dry). Also as Caesalpinaceae.

Nutrition

Synonyms

Also Known As

Algaroba, Algarroba, Algarrobo, Alkharoub, Carrubio, Charoupia, Garrofer, Harip, Harnup, Jarup, Karroub, Keciboynuzu, Kharnub, Kharroub, Locust bean, Locust tree, Rogac, Rožič, St John’s bread, Taratsia, Tikida

References (83)

• ABDELMLUTI,
• Al-Qura'n, S. A., 2010, Ethnobotanical and Ecological Studies of Wild Edible Plants in Jordan. Libyan Agriculture Research Center Journal International 1(4):231-243
• Ali-Shtayeh, M. S., et al, 2008, Traditional knowledge of wild edible plants used in Palestine (Northern West Bank): A comparative study. J Ethnobiol Ethnomed. 4: 13
• Ambasta S.P. (Ed.), 2000, The Useful Plants of India. CSIR India. p 116
• Arora, R. K., 2014, Diversity in Underutilized Plant Species - An Asia-Pacific Perspective. Bioversity International. p 101

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