C. odorata is a large tropical tree up to 40 m tall and a trunk of 2 m in diameter, which produces a light but valuable timber. Native to Latin America where it is well known for its use in cigar boxes and a wide range of other products inc...
C. odorata is a large tropical tree up to 40 m tall and a trunk of 2 m in diameter, which produces a light but valuable timber. Native to Latin America where it is well known for its use in cigar boxes and a wide range of other products including musical instruments, but due to over-exploitation it is also listed on the ‘IUCN Red List of Threatened Species’. It has been widely introduced due to its potential as a plantation species. However, its fast growth has also seen it become an invasive species, especially in the Pacific islands including Hawaii and the Galapagos, and also South Africa.
Cedrela is part of the Meliaceae, or mahogany family, comprising seven species native to tropical South and Central America (Styles, 1981). According to this most recent revision of the genus, Cedrela odorata included 28 other names or synonyms including Cedrela mexicana, however, Cedrela angustifolia, a very vigorous type also in demand because of its resistance to a common insect pest, remained unspecified due to insufficient herbarium material. The result is that C.odorata as now constituted, shows a high degree of variation. Material from West Indian, var. odorata, has glabrous foliage with sessile leaflets, whereas var. mexicana from Central and South America is pubescent, with generally larger leaves with petiolate leaflets, though trees with intermediate characters can be found.
C. odorata is a tree up to 20 m high and with a trunk diameter than can exceed 2 m. Odour is a characteristic of this plant, leaves smelling strongly of garlic or onions, and flowers having a strong malty smell. Leaves are very long, up to 80 cm long, with (5-) 6-7 (-14) pairs of leaflets; leaflets ovate to lanceolate, acute to rounded at base, acute, acuminate or obtuse at tip, 8-20 cm long, 2.5-5.5 (-8) cm broad, generally glabrous. The large and much-branched inflorescences bear numerous small, five-part, symmetrical greenish-white flowers. Flowers are 6-9 mm long; petals greenish-cream in bud becoming white after opening. Fruits are 2.5-4.5 cm long, winged, and septicidally 5-valved. Seeds are flat, chestnut-brown, 20-25 mm long and 6 mm broad including the wing (adapted from PIER, 2008).
Its natural distribution range is confined to the New World, extending from northern Mexico to Argentina, including the Caribbean, approximately between 26°N and 28°S. It is widespread but never very common throughout moist tropical American forests; its numbers are continuing to be reduced by exploitation without successful regeneration (Cintron, 1990).
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.
As a valuable timber tree it is possible that further introductions will occur. However, it is already widespread, and it is recommended that existing trees and stands are monitored for signs of spread.
In its native range, C. odorata is found scattered in moist and seasonally dry sub-tropical or tropical mixed semi-evergreen or semi-deciduous forests on the American mainland, also roadsides, pastures and disturbed areas in the Caribbean, mostly not above 1200 m altitude. It is much more exacting in site requirements as compared to most other Meliaceae, especially drainage, and near the high rainfall limits of its climatic range it is invariably found on ridge tops, upper slopes, ruins, roadsides and other areas of unusually well aerated soil (Cintron, 1990). Where introduced and invasive, it is found in moist uplands in the Galápagos Islands, near sea level in Fiji, and appears well suited to coastal, tropical and sub-tropical areas of Australia including the monsoon zone (PIER, 2008).
Three widely distributed species, C. odorata, C. fissilis and C. angustifolia were observed to hybridize freely, and hybrids could explain the great phenotypic variability in these taxa (Smith, 1960), though there is still no experimental evidence to support or reject the hybridization hypothesis (Cintron, 1990). Recent cytological studies however, have indicated that at least two separate basic diploid chromosome numbers (2n= 50 and 56) occur in C. odorata; which seems widespread in the Meliaceae and may inhibit free hybridization (Styles and Khosla, 1976).
C. odorata begins flowering and fruiting when 10-12 years of age. Throughout its native range it begins flowering at the beginning of the rainy season when new leaves are expanding, being September-October in Argentina, and May-August in Mexico, the Caribbean and northern South America (Cintron, 1990). Trees are monoecious; male and female flowers are borne on the same inflorescence but the species is proterogynous (female flowers open first). Pollination is by small insects and moths (Ward et al., 2005). Fruit development takes 9-10 months and they ripen during the following dry season, with the large woody capsule borne near branch tips. Fruits ripen, split and shed seeds while still attached to the parent tree, opening from the top downward, each releasing 40-50 winged seeds in the dry season. Heavy seed crops are produced annually in some areas and biennially or irregularly in others.Seeds lose viability quickly unless stored very dry at reduced temperatures. Vigorous germination begins with the first rains, with seed viability reportedly up to 90% and rapid germination usually completed within 2-4 weeks, with no dormancy recorded (Cintron, 1990).
Physiology and Phenology
The following is taken from Cintron (1990). Early development of the seedling is rapid with optimal moisture and light. Seedlings can grow both in shade and full sunlight. In natural forests, large numbers of seedling are observed near fruiting trees during the beginning of the rainy season but most of these disappear by the middle or end of the rains. This high natural mortality may be due to shade or competition, or possibly pathogenic diseases such as damping off or other root problems (Cintron, 1990). Seedlings and saplings have extremely shallow root systems and are sensitive to uprooting and root trampling. Seedlings grow to approximately 100 cm tall with a stem diameter of 1 cm or more during the first year under favourable conditions. C. odorata does not coppice readily or produce root suckers though it will pollard and it can be grafted and air-layered (Cintron, 1990). Although tolerant of weeds during the seedling stage, it is considered intolerant of weeds and shade at the sapling stage and beyond. Its thin and spreading crown of light green leaves suggests it is a light demanding species, as does its fast growth and appearance after fire, in hedgerows and on ruins. It is best described as late successional, as it has a moderately long life span (Cintron, 1990).
In Puerto Rico, C. odorata is found in sub-tropical moist and sub-tropical wet zones but is commonest in the sub-tropical moist zone over limestone-derived soils, with other more locally common and frequent trees including Sideroxylon foetidissimum, Dipholis salicifolia, Andira inermis, Terebraria resinosa, Bucida buceras, Clusia rosea, Ochroma pyramidale, Montezuma speciosissima, Coccoloba diversifolia, Zanthoxylum martinicense,Bursera simaruba and Hyeronima clusioides. In continental moist and wet forests, it is also often associated with the more common and frequent mahogany (Swietenia spp.) (Cintron, 1990).
C. odorata is a climatic generalist, found over a wide geographic range of warm latitudinal belts, from sub-tropical dry forests through sub-tropical moist forest to sub-tropical wet forest, to tropical moist and wet and tropical premontane moist and wet zones in equatorial regions. It is most abundant in the lowlands and foothills, and other species such as C.montana and C. lilloi, replace it at higher elevations. Its distribution is within the frost-free tropics for the most part, although it has been collected at latitudes 26°N and 28°S where occasional light frosts can be expected. Mean temperatures of 23° to 26°C are found in the Caribbean part of its range; in tropical South America mean temperature is slightly higher, 28°C with a mean minimum of 23°C and a mean maximum of 32°C. At the southern limit of its range in Argentina the mean temperature is 24°C; mean maximum temperature is 30°C and mean minimum is 18°C (Cintron, 1990). It prefers seasonally dry climates as reflected in its deciduous habit and its formation of (presumably annual) growth rings, preferring annual rainfall of 1200-2400 mm with a dry season 2 to 5 months long, being stunted and slow-growing with 1000 mm, and is only sporadically in areas up to 3500 mm and only on very well-drained sites C. odorata is always found naturally on well-drained soils, often but not exclusively on limestone; or on sites with heavy or waterlogged soils. It may be exacting in its soil requirements but these are still imperfectly understood. In the West Indies it is most commonly found on limestone-derived clay soils but it also grows on well-drained sites over acid soils derived from volcanic rock (ultisols). The common denominators appear to be drainage and aeration of the soil, not soil pH, though no definitive studies of nutrient requirements in the forest has been performed (Cintron, 1990).
By far the most serious insect pest of C. odorata is the mahogany shootborer, Hypsipyla grandella (Cintron, 1990). Larvae of this moth eat the pith just behind shoot growing tips causing death of the apical meristem, slowing plant growth, reducing tree form by promoting multiple leaders or causing seedling mortality. The tree is also attacked by termites and a number of other generalist boring insects and fungal pathogens.
Seeds are winged and thus have evolved for wind dispersal; however, some dispersal by water and wild animals cannot be completely discounted. Long distance dispersal has been entirely due to intentional introduction as a timber species.
As a valuable timber tree, C. odorata has considerable positive economic impacts as a source of revenue for forest-dependent peoples and others along the chain of production. However, there are economic costs where control is needed, such as in the Galapagos Islands, but this must be seen as insignificant in comparison to the globally widespread benefits.
C. odorata is replaces native plants by blocking out sunlight with its large leaves. It can spread very quickly due to prolific seed production and wind dispersal, quickly invading disturbed areas and interferingwith natural succession processes. Dense growths of the plant are likely to increase the frequency and intensity of fires, disturbing the forest further and allowing C. odorata and other invasive plants to become widely established.Invasion ofC. odorata is threatening the native biodiversity of species in transition zone forests on Santa Cruz Island, and is likely to be reducing biodiversity of native species through direct competition in other areas where it is becoming invasive. It does have positive environmental effects also, however, for shade on crops, people and animals.
C. odorata timber, attractive, moderately light (specific gravity 0.4), remains in demand wherever it is available in its native American range. It main uses are in household articles used to store clothing as the heartwood contains an aromatic and insect-repelling resin that is the source of its popular name, Spanish cedar, as it resembles the small or true cedars (Cedrus spp.). The wood works easily and is used for furniture, windows and doors, and is reported to be occasionally used for a wide range of other products. Also, being resistant to fungal decay and termites means it is most suitable for exterior construction, and it makes excellent plywood and veneer and would be more widely used if it could be successfully grown in plantations (Cintron, 1990). It also has a number of uses in traditional medicine. It is an important street tree both in its native and introduced ranges, and has also been used successfully as a shade tree in cacao and coffee plantations (Lemmens et al., 1995).
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.
The regeneration of transition zone forests on Santa Cruz Island, Galapagos, is being monitored following the control of C. odorata, and although control is proving successful, eradication is not considered feasible at present (Rentería et al., 2006).
Seedlings and saplings have extremely shallow root systems and are sensitive to uprooting and root trampling (Cintron, 1990). It is also not resistant to fire, and thus mechanical and fire treatments could prove effective in certain circumstances.
Seedlings can be manually removed, as is practiced in the Galapagos Islands, though larger plants need some form of chemical treatment (Rentería et al., 2006) even though it is noted that they tend not to coppice well.
In the Galapagos, hack and squirt application of 50% Tordon 22K (picloram + 2,4 D) has been found successful, but for trees >40 cm diameter, a 10% mixture of Tordon or Combo (picloram plus metsulfuron) at 20% was found to be effective, or a cut stump treatment of 5% Combo for smaller trees (Rentería et al., 2006).
Although a valuable timber species, control by utilization of the wood would require careful control of the chain of custody, as trade is regulated due to C. odorata being a CITES listed species.