C. verum, the true Ceylon cinnamon tree is native to South Asia, but had already been introduced pan-tropically in the 1700s. The fruit are eaten by birds and spread widely, and it has become invasive on Indian and Pacific Ocean islands,...
C. verum, the true Ceylon cinnamon tree is native to South Asia, but had already been introduced pan-tropically in the 1700s. The fruit are eaten by birds and spread widely, and it has become invasive on Indian and Pacific Ocean islands, especially the Seychelles and Samoa. Once established, it becomes the dominant tree in moist mostly lowland tropical forests, and through competition can gradually affect the species richness of native forest, as the dense canopy shades out all other plants, creating species-poor stands that may cover large areas.
A systematic census of Cinnamomum species used as "cinnamon" spice in northeast India identified 14 taxa (Baruah and Nath, 2007), and 14 were also noted by USDA-ARS (2009). A taxonomic key to differentiate the taxa, formulated on the basis of evaluated characters, is provided by (Baruah and Nath, 2007). However, other sources note very many more, up to about 350 species indigenous to the Asia-Pacific Region and tropical America, with approximately 50 tropical and subtropical trees and shrubs, mostly of economic value. The true cinnamon spice is obtained from C. verum, ‘verum’ derived from the Latin vera, meaning truth, however, marketed cinnamon may also come from a number of other species, notably Cinnamomum cassia.
An evergreen tree up to 18 m tall (in cultivation, it is usually a dense bushy plant about 2-3 m high); bole low-branching, up to 60 cm in diameter; buttresses 60 cm tall, 70 cm deep, thin, light pinkish-brown; bark about 10 mm thick, strongly aromatic; the bark on young shoots is smooth and pale brown, on mature branches and stems rough, dark brown or brownish-grey; oil cells are located in the phloem, and are oval or round in cross-section; wood of mature trees varies from light brownish-grey to grey or yellowish-brown, without markings, more or less lustrous and faintly scented. Leaves opposite, somewhat variable in form and size, strongly aromatic; petiole 1-2 cm long, grooved on upper surface; blade ovate to elliptical, 5-25 cm x 3-10 cm, conspicuously 3-veined, or 5-veined, base rounded, apex acuminate, glabrous, coriaceceous, shiny dark green. Inflorescence consisting of lax axillary or terminal panicles up to 10 cm long or longer; peduncle creamy white, softly hairy, 5-7 cm long; flowers small, 3 mm in diameter, with foetid smell, pale yellow, subtended by small ovate hairy bract; perianth 8 mm long, silky hairy, with short campanulate tube and 6 persistent tepals about 3 mm long; fertile stamens 9, in 3 whorls, with 2 small glands at the base of the stamens of the 3rd whorl; a fourth innermost whorl consists of 3 staminodes; filaments hairy, stout; anthers 4- or 2-celled; ovary superior, 1-celled, with a single ovule, style short. Fruit a 1-seeded berry, ellipsoidal to ovoid, 1-2 cm long, black when ripe, surrounded by the enlarged perianth at the base.
Cinnamon is native to India and Sri Lanka (USDA-ARS, 2009), though it is also considered to be native to the Tenasserim Hills of Myanmar. Cinnamon (C. verum) and cassia (C. cassia) were among the first spices sought after by most early European explorers in the 1400s and 1500s. The Portuguese, occupying Sri Lanka in 1536, and the Dutch, taking over in 1656, established virtual monopolies on the trade. From a product collected from wild stands, it became a cultivated crop in Sri Lanka around 1770. It is likely to be present in many more tropical countries than stated in the distribution table, especially in the Caribbean, Central and South America, and Africa.
The distribution in this summary table is based on all the information available. When several references are cited, they may give conflicting information on the status. Further details may be available for individual references in the Distribution Table Details section which can be selected by going to Generate Report.
Cinnamon (C. verum) had been introduced to the Caribbean by 1762, and the French botanist Jean Baptiste D'Arnault claimed to have collected nutmeg and cinnamon in the Lesser Antilles and Venezuela in 1767 (Zumbroich, 2005). It was introduced into the Seychelles in 1772, and spread so rapidly that already by the end of the 1800s extensive cinnamon forests are said to have already existed. Cinnamon is today the most widely distributed and probably the most numerous plant in the Seychelles from sea level to the highest elevations. Cultivation in Java (Indonesia) began in 1825 but, after initial success, declined rapidly. Subsequently, Ceylon cinnamon has been taken to many countries (Seychelles Ministry of Environment, undated).
The native habitat of C. verum in principally tropical rainforest, but it can also be found, especially as an introduced invasive, in other forests, particularly moist secondary forests, forest gaps, rock outcrops and riparian zones (PIER, 2009).
The genus Cinnamomum is open-pollinated, and pollination is most probably by insects, especially flies. Fruits mature in six months. Propagation is mainly by seed, and as the fruits are much liked by birds, the seed is easily spread, though they quickly lose their viability. Vegetative propagation is possible, by cuttings, layering or division of old rootstocks.
Germination of seeds of the closely related C. camphora appears to be inhibited while the seed remains in contact with the flesh of ripe fruits, which appear to release inhibitory substances (Firth, 1979).
Physiology and Phenology
Seedling root growth is initially rapid, with the formation of a well-developed taproot followed by numerous spreading laterals, leading to a moderately deep and extensive root system. There is normally a single central stem, but in cultivation trees are coppiced. The uncut tree has numerous, often drooping, branches beginning low on the trunk. Growth takes place in flushes, young leaves being reddish in colour, later turning dark green.
Competition between the endemic palm Phoenicophorium borsigianum and the aggressively invasive alien C. verum in the Seychelles was found to be greatly influenced by the amount of available photosynthetically active radiation (Fleischmann et al., 1999). Both species showed a negative correlation between mean leaf area of seedlings and light levels. P. borsigianum responded significantly better to low gap light levels than C. verum and both species showed no further response to high levels of direct sunlight. P. borsigianum and probably other endemic palms act as a filter affecting the distribution and abundance of establishing C. verum seedlings. Mortality of C. verum was strongly negatively correlated with levels of photosynthetically active radiation, whereas P. borsigianum showed no such correlation (Fleischmann et al., 1999).
Cinnamomum is adapted to a wide range of climatic conditions. Cinnamon requires a warm and humid climate with a well distributed annual rainfall of around 2000-2500 mm, and average temperatures of about 27°C. Wild cinnamon trees are adapted to tropical evergreen rainforests. It grows best at low altitudes, and is usually grown without shade, but being essentially a forest tree, light shade is tolerated. It grows well on different soils in the tropics, but soil type has a pronounced effect on bark quality. Fine sandy and lateritic gravelly soils rather than rocky and stony substrates are best in Sri Lanka and India, but in the Seychelles and Madagascar more loamy soils are preferred. Cinnamon is considered susceptible to salinity, and a bitter product results from waterlogged and marshy conditions.
These ecological aspects are more or less the same for both cinnamon and cassia, although cassia is somewhat less specific than cinnamon. The species occurs up to 2000 m altitude, on well-drained hillside soils of low fertility and pH 4-6 (Ravindran, 2017).
Stripe canker (Phytophthora cinnamomi) may damage trunks and branches of young trees in particular, symptoms being vertical strips of dead bark, particularly near ground level. Root rots include black rot caused by Rosellinia spp., brown rot caused by Phellinus lamaensis, and white rot caused by Fomes lignosus. Pink disease (Corticium salmonicolor) causes pink encrustations on the stem with death of small shoots. Glomerella cingulata causes anthracnose. Rust (Aecidium cinnamomi) and other leaf and stem diseases (Cephaleuros virescens, Diplodia spp., Exobasidium spp., Gloeosporium spp., Leptosphaeria spp. and Pestalotia cinnamomi) may occasionally cause damage.
In India and Sri Lanka, caterpillars of the cinnamon butterfly (Chilasa clytia) are destructive to new flushes, and shothole borers (Xylosandrus spp.) cause damage to stem and bark. Leaf miners (Acrocercops spp., Phyllocnistischrysophthalma), gall and leaf mites (Eriophyes bois, E. doctersi, Typhlodromus spp.), leaf webbers (Sorolophaarchimedias) and arboreal ants (Oecophylla smaragdina) cause occasional damage. Young seedlings are vulnerable to damage by agrotid larvae or mole crickets (Gryllotalpa spp.), and larvae of Popillia spp., attacking roots. Ceylon cinnamon is also attacked by root-knot nematodes (Meloidogyne spp.). Storage pests of cinnamon quills include Lasioderma serricorne, Pyralis ferinalis and Sitodrepa panicea.
Whereas no specific data is available for C. verum, fruit of the closely related C. camphora can float for up to 20 days in water with no effect on germination, thus water dispersal is possible (Firth, 1979).
Vector Transmission (Biotic)
Propagation is mainly by seed, and the fruits are much liked by birds and the seed is easily spread, though seeds quickly lose their viability. Vegetative propagation is possible by cuttings, layering or division of old rootstocks, and so it could be spread by vegetative means.
The fruits of C. verum have a particularly high nutritional quality, with individual berries containing 3.5 times more protein and 55 times more lipid than the median values of the native species, and thus it is considered more attractive to birds than native species (Kueffer et al., 2009). There appears to be a general tendency for native island plants to produce fruits of low energy content, perhaps reflecting reduced competition for dispersal agents on isolated islands, and invasive species were found to consistently produce fruits with a lower water content, resulting in a higher relative yield (i.e. dry pulp weight to total wet fruit weight ratio), and a higher energy content.
C. verum is highly valued as a commercial spice, and as such it was widely introduced around the tropical world by early explorers during the 1700s and 1800s.
Being highly valued as a commercial spice, C. verum has strong positive economic impacts. Production data from the main exporting countries are detailed in FAOSTAT (2008). Sri Lanka produces the largest quantity and the best quality of bark of Ceylon cinnamon, mainly as quills. Other products include cinnamon leaf oil, and cinnamon bark oil and oleoresin are mainly prepared in importing countries. The USA and western Europe are the main markets for oils. Cinnamon bark oil is very expensive, reflecting the high raw material cost, whereas cinnamon leaf oil is much cheaper, but still more expensive than clove leaf oil, an alternative source of eugenol.
In the Seychelles, the aggressive C. verum has invaded mountain mist forest and intermediate forest habitats and threatens several endemic palm species, notably Phoenicophorium borsigianum , but also Deckenia nobilis and Roscheria melanochaetes (Fleischmann et al., 1999) and other native trees such as Northea hornei (Kueffer et al., 2008). C. verum is likely to persist as a major invader on Silhouette Island, Seychelles, due to wider seed dispersal, but the stability of the native forest composition in most areas was confirmed over a 10-year period over this time-scale (Gerlach, 2004).
Plant species invading nutrient-poor ecosystems are likely to have their greatest impact on the native plant community by competing for resources below-ground. In an infertile, phosphorus-poor ecosystem in the Seychelles, the dense topsoil root mat produced by mature C. verum trees suppressed growth of young trees, mainly by increasing competition for scarce nutrients (Kueffer et al., 2007). Stands of C. verum exerted a strong below-ground filtering effect on seedling regeneration and influenced secondary forest succession by selectively reducing the establishment of invasive and small-seeded species, exerting a strong influence on forest regeneration (Kueffer et al., 2007).
Some invasive alien plants such as C. verum accelerate nutrient turnover in the ecosystem because the litter they produce has a high specific leaf area, high concentrations of nutrients and low concentrations of lignin and polyphenolics, and thus they decompose rapidly. Such litter properties are typical of plants from nutrient-rich but not nutrient-poor ecosystems, and species that successfully invade nutrient-poor ecosystems might not exhibit them (Kueffer et al., 2008). Even on the very nutrient-poor soils of the granitic Seychelles, pioneer invasive species like C. verum produce more decomposable litter and therefore have the potential to alter rates of nutrient cycling. However, the small differences in soil fertility beneath native and invasive trees suggest that impacts of invasive species on nutrient cycling are more complex and less predictable in nutrient-poor ecosystems, where several nutrients may be co-limiting, and native and alien species coexist (Kueffer et al., 2008).
The spice (Ceylon) cinnamon is the dried inner bark of C. verum. The major uses of cinnamon, both in whole and ground form, are for domestic culinary purposes and for flavouring processed foods (bakery products, sauces, pickles, puddings, beverages, confectionery), in perfumes, pharmaceutical products and in incense. Cinnamon bark is an important folk medicine. Cinnamon bark is astringent, stimulant and carminative. It can also stop nausea and vomiting. The bark can further be used for the distillation of bark oil and for the preparation of solvent-extracted oleoresin. The leaves are used for distillation of leaf oil, which has a different composition than bark oil. The dried inner bark of Ceylon cinnamon contains steam-volatile oils, fixed oils, tannin, resin, proteins, cellulose, pentosans, mucilage, starch, calcium oxalate and minerals. It is phytochemically interesting, however, that the same tree species produces three distinct essential oils, characterized by eugenol in the leaves, cinnamaldehyde in stem bark, and camphor in root bark. The essential oil content varies from 0.5-2.0% in bark and 0.7-1.2% in leaves. Cinnamon and cassia barks are interchangeable in many applications, and the same applies to cinnamon bark oil, cassia bark oils and (Chinese) cassia leaf oil.
As a source of eugenol, however, cinnamon leaf oil has lost ground to the cheaper clove leaf oil, except when the eugenol is needed for conversion into isoeugenol (used in confectionary products). The oleoresin is used mainly by the flavour industry in western Europe and North America for flavouring processed foods and in the soft-drink industry. Cinnamon bark oil is used in flavouring (processed foods, beverages, dental and pharmaceutical preparations), much less in perfumery because it has some skin-sensitizing properties. As a powerful local stimulant it is sometimes prescribed in gastrodynia, flatulent colic and gastric debility. In European phytomedicine, cinnamon bark oil (0.05-0.2 g daily intake) is used in teas and other galenicals for its antibacterial, carminative, and fungistatic properties, and also for loss of appetite and dyspeptic disturbances. The maximum permitted level in food products is 0.06%. Cinnamon leaf oil is used in flavouring and perfumery, and as a source of its major constituent eugenol. Eugenol is used for the synthesis of vanillin, and for conversion into iso-eugenol, used for flavouring confectionary products. Cinnamon leaf oil is extensively used as a fragrance component in soaps, detergents, cosmetic and alcoholic perfumery, with a maximum permitted level of 0.8% in the perfume.
Ceylon cinnamon has to be harvested during the wet season because then the cambium is active and the cortex can be easily separated from the wood. The shoots are harvested when they are 2-3 m tall and 1.2-5.0 cm in diameter. Shoots in the centre of the clump are cut low down, while those on the outside are cut higher up to ensure that new buds sprout mainly on the outside of the clump. In Sri Lanka, harvest peaks are in May-June and October-November. The first harvest is of inferior quality (thick bark), but this improves in later harvests. Best quality cinnamon is obtained from thin bark from the middle part of shoots in the centre of the stool. Leaves and twigs are cut off and used for mulching, or the leaves are retained for distillation. The harvested shoots are bundled and taken to a processing unit for peeling and further preparation.
The seeds contain about 30% fixed oil, used in India for candle making. The oil is obtained by boiling crushed ripe fruits. The timber is light to moderately heavy (specific gravity 0.5-0.7), usually straight-grained, even-textured, and weak. It seasons easily but warps, splits, cracks and stains. It is suitable only as low-grade board wood.
Several species of Cinnamomum are equally aromatic and also invasive, for example C. camphora and C. burmanni (PIER, 2009). For a taxonomic key to differentiate Cinnamomum species, see Baruah and Nath (2007).
Due to the variable regulations around (de)registration of pesticides, your national list of registered pesticides or relevant authority should be consulted to determine which products are legally allowed for use in your country when considering chemical control. Pesticides should always be used in a lawful manner, consistent with the product's label.
There is limited information on control of C. verum, though strategies for controlling invasive species in the Seychelles including C. verum are detailed in Vielle and Mauremootoo (2003), and management schemes were proposed. As such, information below is on the control of the closely-related invasive tree C. camphora.
C. camphora was controlled in Australia by hand pulling and intensive grazing before the dairy industry declined in the 1960s (Firth, 1981). As seeds can be dispersed by water, C. camphora should be removed from the vicinity of streams and watercourses. Expansion of the horticulture industries and closer settlement in 1980-90 helped to reduce spread of the species in some areas, and revegetation programmes for native rainforest regeneration have been advocated to reduce the spread of C. camphora. Felling of trees is ineffective because of the prolific regrowth from cut stumps Clearing of stands of camphor by bulldozer is effective, but expensive and an erosion hazard on steeper slopes. Replacement of the species with sown pasture species or native trees reduces regeneration and recolonization.
Effective chemical control is obtained by overall spraying of seedling trees up to 3 m height with triclopyr + picloram, or a strong solution of glyphosate, taking care to avoid spraying near watercourses. Established trees are killed by injecting with concentrated solutions of glyphosate, triclopyr or picloram making sure that the chemical is administered around the entire circumference of all stems below approximately 1 m from the ground (Firth, 1986).
Noting the economic value of cultivated cinnamon even on islands where it is invasive, it may be unlikely that the release of biological control agents would ever be acceptable.
Abdel Hafez SII, El Said AHM, 1997. Effect of garlic, onion and sodium benzoate on the mycoflora of pepper, cinnamon and rosemary in Egypt. International Biodeterioration and Biodegradation. 39: 1, 67-77; 41 ref.