Cinnamomum camphora (Camphor Laurel)

Scientific name

Cinnamomum camphora (L.) Nees & Eberm.

Synonyms

Camphora camphora (L.) H. Karst.; Camphora officinarum Nees; Cinnamomum camphoroides Hayata; Cinnamomum officinalis Nees ex Steud.; Cinnamomum officinarum Bauh.; Laurus camphora L.; Persea camphora (L.) Spreng.

Common names

Camphor laurel, camphor, camphor tree, camphortree, Formosa camphor, gum camphor, Japanese camphor, shiu leaf, true camphor

Family

Lauraceae

Origin

Native to eastern Asia.

Naturalised distribution (global)

Locations within which Cinnamomum camphora is naturalised include Australia, southern USA, southern Europe, southern and eastern Africa, Madagascar and some oceanic islands with warm climates.

Introduced, naturalised or invasive in East Africa

Cinnamomum camphora is invasive in parts of Kenya (CABI CPC 2007) and Tanzania (A.B.R. Witt pers. obs., TBA 2005). The editors are not aware of records of the presence of C. camphora in Uganda, though this does not necessarily mean that it is absent from the country.

Habitat

A weed in neglected areas near habitation, on street verges, along roadsides, in native bushland, rainforest edges and gaps, moist open woodlands, pastures, and especially riparian zones (banks of watercourses).

Description

Cinnamomum camphora is a large and spreading tree, often growing 15-30 m tall. The rough bark is light brown or greyish-brown in colour, scaly or fissured, and has a strong odour (it is highly aromatic). Young branches are green or reddish-green in colour, rounded and hairless (glabrous).

The leaves are alternately arranged, but sometimes densely clustered (pseudo-whorled), with leaf stalks (petioles) 15-40 mm long. These leaves (4.5-11 cm long and 2.4-6 cm wide) vary from oval (elliptic) to broadly egg-shaped in outline with broad end at base (broadly ovate) and have three distinct veins spreading from their bases. Their upper surfaces are bright green and glossy, while their undersides are paler green and duller in nature. They are hairless (glabrous) with entire margins that are often wavy (undulating), and have pointed tips (acute apices). The leaf buds are enclosed in distinctive overlapping scales when they are young. Oil glands and two small raised swellings (domatia) are evident on the undersides of the leaves, if they are observed with a hand lens.

The flowers are small with six whitish, greenish-white or pale yellowish 'petals' (perianth lobes) 1.5-3 mm long. They also have 5-9 stamens. These flowers are borne in small branched clusters (about 7.5 cm long) at the tips of the branches (in terminal panicles).

The fruit look like 'berries', but they are actually drupes containing a hard centre. These fruit are globular (8-10 mm across), glossy in appearance, and turn from green to black as they mature. They are attached to the stem by an enlarged, greenish-coloured, cone-shaped or cup-like structure (a conical or cupular receptacle) that is about 5 mm across.

Reproduction and dispersal

This plant reproduces by seed, which are most commonly spread by birds, but may also be dispersed by water, other animals, and in dumped garden waste. Suckers are also readily produced, particularly when older trees are poisoned, damaged or cut down.

Similar species

There are several closely related native species which can be confused with Cinnamomum camphora. However, most of these can be separated by the fact that they do not give off a strong camphor smell when their leaves are crushed. Cinnamomum oliveri (Oliver's sassafras) does have a strong camphor smell, however its leaves are oppositely arranged, or nearly so, and they are narrower than the leaves of C. camphora.

Economic and other uses

Widely cultivated as a street and garden tree, C. camphora is cultivated for camphor, which is used as a culinary spice, a component of incense, and as a medicine. Camphor is also an insect repellent and a flea-killing substance.

Environmental and other impacts

Cinnamomum camphora is a large tree that aggressively invades moist gullies, open woodlands, rainforest margins, and riparian zones (banks of watercourses). It creates a dense canopy, competes with and replaces native species, and continues to inhibit their regeneration even after it has been removed. Mature C. camphora trees develop a massive root system which has the potential to block drains and crack concrete pavements. The fruit, leaves, and roots are also toxic to humans if ingested in sufficient doses.

C. camphora has been listed in the Global Invasive Species Database (GISD 2005). It has been listed as noxious weed in South Africa and New South Wales and Queensland, Australia.

Management

The precise management measures adopted for any plant invasion will depend upon factors such as the terrain, the cost and availability of labour, the severity of the infestation and the presence of other invasive species. Some components of an integrated management approach are introduced below.

The best form of invasive species management is prevention. If prevention is no longer possible, it is best to treat the weed infestations when they are small to prevent them from establishing (early detection and rapid response). Controlling the weed before it seeds will reduce future problems. Control is generally best applied to the least infested areas before dense infestations are tackled. Consistent follow-up work is required for sustainable management.

Clearing or removal of large stands of the species is expensive. Cutting down trees alone is ineffective because of the prolific regrowth from cut stumps. Stumps can be treated with herbicide to prevent regeneration. Effective control of trees up to 3 m height can be obtained by spraying with a suitable herbicide, taking care to avoid spraying near watercourses. Established trees can killed by injecting with concentrated solutions of a suitable herbicide making sure that the chemical is administered around the entire circumference of all stems below approximately 1 m from the ground. When using any herbicide always read the label first and follow all instructions and safety requirements. If in doubt consult an expert.

Replacement of the species with sown pasture species or native trees reduces regeneration and recolonisation.

The editors could find no information on any biological control agents for this species.

Legislation

Not listed as a noxious weed by the state or governments in Kenya, Tanzania and Uganda.

References

CABI invasive species compendium online data sheet. Cinnamomum camphora (camphor laurel). CABI Publishing 2011. www.cabi.org/ISC. Accessed March 2011.

Germplasm Resources Information Network (GRIN). www.ars-grin.gov/npgs/index.html. National Germplasm Resources Laboratory, National Genetic Resources Program, Agricultural Research Service (ARS), United States Department of Agriculture (USDA), Beltsville, Maryland, USA. Accessed March 2011.

GISD (2005). Global Invasive Species Database online data sheet. Cinnamomum camphora (tree). www.issg.org/database. Invasive Species Specialist Group. Accessed March 2011.

Global Compendium of Weeds. www.hear.org/gcw. Hawaiian Ecosystems at Risk Project. Accessed March 2011.

Global Compendium of Weeds. www.hear.org/gcw. Hawaiian Ecosystems at Risk Project. Accessed March 2011.

Henderson, L. (2001).  Alien weeds and invasive plants. A complete guide to declared weeds and invaders in South Africa.  Plant Protection Research Institute Handbook No. 12, 300pp. PPR, ARC South Africa.

Lazarides, M., Cowley, K. and Hohnen, P. (1997). CSIRO Handbook of Australian Weeds. CSIRO Publishing, Collingwood, Victoria.

Pacific Island Ecosystems at Risk (PIER). Cinnamomum camphora (L.) J.Presl, Lauraceae: plant threats to Pacific ecosystems. www.hear.org/pier/species/cinnamomum_camphora.htm. Institute of Pacific Islands Forestry, Hawaii, USA. Accessed March 2011.

TBA (2005). Effect of shade on leaf length, leaf area, stem diameter and coverage of Lantana camara under Maesopsis eminii and Cinnamomum camphora dominated sites in Amani Nature Reserve, East Usambara Mountain, Tanzania.

Editors

Agnes Lusweti, National Museums of Kenya; Emily Wabuyele, National Museums of Kenya, Paul Ssegawa, Makerere University; John Mauremootoo, BioNET-INTERNATIONAL Secretariat - UK.

Acknowledgments

This fact sheet is adapted from The Environmental Weeds of Australia by Sheldon Navie and Steve Adkins, Centre for Biological Information Technology, University of Queensland. We recognise the support from the National Museums of Kenya, Tropical Pesticides Research Institute (TPRI) - Tanzania and Makerere University, Uganda. This activity was undertaken as part of the BioNET-EAFRINET UVIMA Project (Taxonomy for Development in East Africa).

Contact

BioNET-EAFRINET Regional Coordinator: eafrinet@africaonline.co.ke