Carob Tree (Ceratonia siliqua) Botanical Characteristics
Carob (Ceratonia siliqua L.) is one of the most characteristic trees of the Mediterranean maquis, which belongs to the legume family (Fabaceae). It is easily distinguished from other fruit trees by its thick and cracking trunk, leathery hard and shiny leaves, small flowers without a crown blooming on the trunk and old branches, and a long, flat pod.
In this article, we discuss the scientific classification of carob, the general structure of the tree, the morphology of leaves, flowers, fruits and seeds, and its basic characteristics such as height and lifespan in the light of botanical sources. We leave the cultivation details to our related articles.
Scientific Classification of Carob
Carob is known as Ceratonia siliqua L. in the scientific world. The Kew Botanic Gardens' plant database, Plants of the World Online (POWO), records that the species has the accepted name Ceratonia siliqua L., belongs to the family Fabaceae, and was first published in 1753 in Linnaeus' Species Plantarum. The same source defines the natural distribution of the species as the region stretching from the Mediterranean to Iran.
The genus name Ceratonia is derived from the Greek word keras, meaning "horn"; the species name siliqua is derived from the Latin word meaning pod or shell. Together, these two names refer to the hardness of the fruit and its horn-like shape (Batlle and Tous, 1997). The Turkish name "carob" was born from the same analogy. In Günal's study, it is stated that the species is also known by local names such as carob, honeybaba, honey horn and mad horn in our country.
According to the comprehensive monograph published by the International Institute of Plant Genetic Resources (IPGRI), carob is placed in the subfamily Caesalpinioideae of the legume family and is generally considered within the Cassieae tribe. However, some researchers find the place of the genus in this tribe controversial. In the monograph, it is emphasized that Ceratonia is seen as one of the most archaic genera of legumes and that it is taxonomically isolated from other genera of the family (Batlle and Tous, 1997).
| Steps: | Carob |
|---|---|
| Family | Fabaceae (Leguminosae, legumes) |
| Subfamily | Caesalpinioideae |
| Genus | Ceratonia L. |
| Type | Ceratonia siliqua L. |
| Closely related species | Ceratonia oreothauma (Oman and Somalia) |
Second Species of the Genus: Ceratonia oreothauma
Ceratonia, which was long considered a uniform genus, was added to a second species in 1980. Two subspecies of this species, called Ceratonia oreothauma, have been described: subsp. oreothauma, which grows in Oman, and subsp. somalensis, which grows in northern Somalia. This species differs distinctly from carob morphologically; its pollen grains are slightly smaller and structurally different. Some researchers have therefore suggested that C. oreothauma may be the wild ancestor of carob in culture (Batlle and Tous, 1997; Dahmani et al., 2023). However, this view is not conclusive; the origin of the species is still a subject of debate.
General Structure of the Tree: Height, Trunk and Crown
Carob is a shrub or tree with hard leaves (sclerophyll) and evergreen. The IPGRI monograph states that the tree can grow up to 10 meters tall, forms a wide hemispherical crown, has a thick trunk, brown and rough bark, and sturdy branches (Batlle and Tous, 1997). In the 2023 review by Dahmani et al., it is stated that the tree can reach up to 15 meters. In the investor guide of the Ministry of Agriculture and Forestry, a tree that can grow 12-15 meters tall, has a gray-brown trunk, thick branches and a wide top. These differences indicate that the tree can reach very different sizes depending on the environment in which it grows, its age and the way it is cared for.
In its natural distribution areas in Turkey, carob is often seen as a tree as a maquis element; in protected areas, it reaches the form of a real tree. Günal states that carob with a height of 6-8 meters and a diameter of 1-1.5 meters is found in afforested communities on the Dilek Peninsula thanks to conservation. In the Bozburun Peninsula and some villages of the Teke Peninsula, centuries-old, monumental trunks attract attention.
The appearance of the trunk changes markedly with age. In young trees, the bark is flat and gray, but as it ages, it becomes brown and rough. Dahmani et al. state that the thick, deeply cracked and twisted trunk of mature trees resembles an olive tree, and the circumference of the trunk base can reach 2–3 meters. The wood is initially yellowish-white in color, with pink veins with age, then dark red and hard.
A recent study conducted on 45 genotypes selected from the natural population in Antalya's Serik district revealed that there are large differences even between trees in the same region. In these genotypes, the trunk circumference ranged from 45 to 268 cm, 60 percent of the genotypes showed upright growth, and 60 percent had a multi-stemmed structure (Pepe & Yıldırım, 2026).
Root system
The basis of carob's drought resistance lies in its deep-seated root system. Dahmani et al. report that the tree has developed a tap-root system that can reach a depth of 18 meters. In the ministry guide, it is stated that the roots can go 15-20 meters deep from the soil surface. The IPGRI monograph states that the rooting habit of carob is similar to pistachio and that it sends roots to deeper soil layers in order to find water under stress conditions.
Although it is from the legume family, carob does not form the root nodules seen in many members of this family and cannot bind the nitrogen of the air. It has been determined that its roots can establish symbiosis with arbuscular mycorrhizal fungi (Batlle and Tous, 1997).
Life span
Carob is a slow-growing and long-living tree. Dahmani et al. state that the tree can produce for a long period of time, such as 100-150 years, and its lifespan can extend up to 500 years. The monumental carob trees seen in the coastal villages of our country are also living examples of this long life.
Leaf Structure
The leaves of the carob are compound and alternately arranged on the branches. According to the IPGRI monograph, the leaves are 10–20 cm long; there may or may not be a single leaflet at the tip. The leaflets are 3–7 cm long, egg-shaped or elliptical, and usually arranged in 4–10 opposite pairs (Batlle and Tous, 1997). The leaflet length measured in the Serik population ranged from 37.52–75.36 mm and width ranged from 24.23–54.63 mm (Pepe & Yıldırım, 2026).
The leaflets are thick and hard like leather. The upper sides are dark green and shiny, and the lower sides are lighter green. Its edges may be slightly wavy. This sclerophyll structure is an adaptive response to the hot and dry summers of the Mediterranean. In the monograph, it is stated that the upper epidermis is very thick and its cells contain phenolic compounds, while the pores (stomata) are found only on the underside of the leaf and in clusters.
Carob does not shed its leaves in autumn. The leaves usually live for two years; in early summer, around July, some of the two-year-old leaves fall off, while regeneration occurs partially in spring (Batlle and Tous, 1997). The tree undergoes two shoot periods in spring and autumn, as in most Mediterranean trees; when the temperature drops below 10 °C, vegetative growth slows down.
Flower Structure and Flowering
Carob flowers are small and numerous. According to the IPGRI monograph, the flowers are 6–12 mm long and are arranged spirally on catkin-like inflorescences that emerge from short shoots on old wood or even directly from the stem. The formation of flowers on stems and old branches is called kauliflori in botany and is a clear clue to recognizing carob.
The flowers are reddish-green in color and have no petals. The flower with quintuple symmetry has a disc-shaped, nectar-secreting bowl. Dahmani et al. stated that there are usually 15–40 flowers in a cluster; Dafni et al., on the other hand, state that strong-smelling clusters carry about 20–50 flowers.
Carob flowers are structurally divided into three types:
| Female flower | It consists of a female organ (pistil) and vestigial male organs on a disc; the curved ovary consists of two carpels. |
| Male flower | Around the nectar disc are five thinly pedunculated stamens; in the middle is a vestigial pistil. |
| Hermaphrodite flower | It bears both a developed pistil, and five stamens. |
Carob is largely a dioecious species; that is, male and female flowers are usually found on separate trees. In addition, there are trees that bear herbaceous flowers. Although flowers are bisexual at the beginning of development, they become functionally male or female with the suppression of a sex in the later stages of development (Batlle and Tous, 1997). We discuss this subject in detail in our article "Male, Female and Male Trees in the Carob Tree".
Another feature that makes carob special among Mediterranean trees is that the main flowering period falls in autumn, approximately September-November. In the monograph, it is emphasized that carob is the only tree in the Mediterranean in this regard and is similar to many tropical plants. We examine the flowering and pollination process in a separate article.
Fruit (Pods) Morphology
The fruit of the carob is an indehisent pod that does not open spontaneously when ripe. According to the IPGRI monograph, the pod is long, flat, straight or curved, thickened at the seams; It reaches a length of 10–30 cm, a width of 1.5–3.5 cm and a thickness of about 1 cm, with a blunt or slightly pointed tip. Ripe pods are brown, wrinkled with a surface and leathery consistency (Batlle and Tous, 1997). The tree database of the World Agroforestry Centre gives the same measurements (Orwa et al., 2009).
The fleshy part of the pod (pulp) consists of a hard layer like skin on the outside (pericarp) and a softer area on the inside (mesocarp). The seeds are arranged transversely inside the pod and separated from each other by mesocarp tissue. Dahmani et al. report that there are usually 4–15 seeds in a pod.
The development of pods requires a long process. In the monograph, it is explained that after fertilization in autumn, there is almost no increase in the weight of the pod during the winter, it enters a rapid growth phase in spring (April-June), growth slows down and maturation begins in June, and the color changes from green to brown. It takes about 10 months for pods to mature. While the water content in green pods is about 70 percent, this rate decreases to 12-18 percent in mature pods (Batlle and Tous, 1997).
Pod sizes vary greatly according to the variety and growing condition. In a study conducted in Turkey, the average pod weight of wild genotypes was measured as 63.72 g, and that of grafted genotypes was measured as 107.61 g (Tetik et al., 2011). We discuss the differences between wild and grafted carob in a separate article.
Pulp and Seed Ratio
The fleshy part of the pod constitutes most of the weight in terms of weight. In the IPGRI monograph, it is stated that the seed ratio in Mediterranean varieties varies between 5 and 27 percent, and the pulp rate is in the range of 73-95 percent. Dahmani et al. state that seeds constitute 8-12 percent of the pod weight in grafted varieties and 16-20 percent in ungrafted wild types. These ratios are important because they determine the value of both the pulp and the seed from a commercial point of view.
Seed Structure
The carob seed is hard, shiny brown and flat-oval in shape. According to the IPGRI monograph, the seeds are 8–10 mm long, 7–8 mm wide and 3–5 mm thick; the seed coat (testa) is hard and smooth, the belly (hilum) is very small (Batlle and Tous, 1997). The World Agroforestry Centre database records that there are about 500 seeds in one kilogram (Orwa et al., 2009).
Since the hard shell of the seed does not pass water easily, the seeds germinate slowly and irregularly without pre-treatment. The internal structure consisting of the seed coat, endosperm and embryo makes the seed valuable for industry. Detailed structure and usage areas of the seed What is Carob Seed? You can find it in our article and how to grow seedlings from seeds in our related article.
Natural Distribution and Ecological Location
The origin of carob is not known for certain. Some researchers have placed the species' homeland in the eastern Mediterranean (Turkey and Syria), while others have pointed to the south of the Arabian Peninsula. The IPGRI monograph states that the wild distribution of the species includes Turkey, Cyprus, Syria, Lebanon, Israel, southern Jordan, Egypt, Arabia, Tunisia, and Libya, and that it spread early to the west.
Carob, together with wild olive and mastic tree, forms one of the most characteristic communities (Oleo-Ceratonion) of the lower belt of Mediterranean vegetation. According to the Ministry's guide, its natural distribution in our country starts from the Urla-Karaburun peninsula of Izmir and extends to the Syrian border in Hatay, following the Aegean and Mediterranean coastlines. Günal states that the area where the species is most concentrated in the Mediterranean Region is between Antalya and Silifke. We explain the climate and soil requirements of the species in detail in our separate articles.
Frequently Asked Questions
What family does carob belong to? Carob belongs to the legume family (Fabaceae or Leguminosae) and is in the subfamily Caesalpinioideae of this family.
How tall is a carob tree? Sources give different values: The IPGRI monograph states that it can grow up to 10 meters, Dahmani et al. up to 15 meters. In natural maquis areas, it mostly remains in the form of trees or shrubs.
Does carob shed its leaves? Carob is an evergreen tree; its leaves live for about two years and are partially shed in early summer and partially renewed in spring.
Why do carob flowers bloom on the stem? Carob flowers form on short shoots on old wood and directly on the stem. This feature is called kauliflori and is one of the distinctive botanical features of the species.
Get to Know Carob Closely with Carob Türkiye
Knowing the botanical characteristics of the carob tree makes it easier to understand why the fruit is so resistant, nutritious and industrially valuable. Long-lived, drought-resistant and capable of producing even in poor soils, it is part of the natural heritage of our Mediterranean coast.
At Carob Türkiye, we supply carob fruit, crumbs, flour/powder, kernels and extracts. For general characteristics of carob What is Carob? You can read our article, our products Carob Fruit and Our Products You can review it on the pages. For your wholesale and export requests Contact Now You can contact us on our page.
Domestic resources
Republic of Turkey Ministry of Agriculture and Forestry, General Directorate of Forestry, "Carob Orchard Facility Project Feasibility Report and Investor Guide", Ankara, 2020. Eskisehir.
agriculture. gov. en/ DocumentsArchive/ Yat%C4%B1r%C4%B... Günal, N., "Carob (Ceratonia siliqua L.)' s Geographical Distribution, Ecological and Floristic Characteristics in Turkey", Marmara Geographical Journal, Issue 2, pp. 60–74, 1998. dergipark.
org. en/ en/ pub/ marucog/ article/ 560542 Pepe, A. V., Yıldırım, F., "Morphological Characteristics of Naturally Growing Carob (Ceratonia siliqua L.) Genotypes in Serik District (Antalya/Türkiye)", Turkish Journal of Science and Engineering, 8(1), 52–59, 2026. doi.
org/ 10. 55979/ tjse. 1956615 Tetik, N., Turhan, İ., Oziyci, H. R., Gübbük, H., Karhan, M., Ercişli, S., "Physical and chemical characterization of Ceratonia siliqua L. germplasm in Turkey", Scientia Horticulturae, 129(4), 583–589, 2011. doi.
org/ 10. 1016/ j. Scienta. 2011. 04. 029 Foreign sources
Batlle, I., Tous, J., "Carob tree. Ceratonia siliqua L. Promoting the conservation and use of underutilized and neglected crops. 17", Institute of Plant Genetics and Crop Plant Research, Gatersleben / International Plant Genetic Resources Institute, Rome, 1997. ISBN 92-9043-328-X. hdl.
handle. net/ 10568/ 104277 Dahmani, W., Elaouni, N., Abousalim, A., Akissi, Z. L. E., Legssyer, A., Ziyyat, A., Sahpaz, S., "Exploring Carob (Ceratonia siliqua L.): A Comprehensive Assessment of Its Characteristics, Ethnomedicinal Uses, Phytochemical Aspects, and Pharmacological Activities", Plants, 12(18), 3303, 2023. doi.
org/ 10. 3390/ plants12183303 Orwa, C., Mutua, A., Kindt, R., Jamnadass, R., Simons, A., "Agroforestree Database: a tree reference and selection guide, version 4.0 – Ceratonia siliqua", World Agroforestry Centre, 2009. apps.
worldagroforestry. org/ treedb2/ AFTPDFS/ Ceratonia_sili... Royal Botanic Gardens, Kew, "Ceratonia siliqua L.", Plants of the World Online (POWO), accessed 2026. powo.
science. kew. org/ taxon/ 485647- 1 Dafni, A., Marom-Levy, T., Jürgens, A., Dötterl, S., Shimrat, Y., Dorchin, A., Kirkpatrick, H. E., Witt, T., "Ambophily and 'super generalism' in Ceratonia siliqua (Fabaceae) pollination", Evolution of Plant-Pollinator Relationships (Systematics Association Special Volume 81), Cambridge University Press, pp. 344–373, 2011. doi.
Scientific Resourcesorg/ 10. 1017/ CBO9781139014113. 013
