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Syzygium cordatum Hochst. ex C.Krauss

Protologue
Flora 27: 425 (1844).
Family
Myrtaceae
Vernacular names
Water berry, water wood, water tree (En). Timuncho (Po). Mzambarau-ziwa, myamayu, mlati (Sw).
Origin and geographic distribution
Syzygium cordatum is distributed from DR Congo eastward to Kenya and southward to South Africa.
Uses
The wood is used for mortars, utensils, construction, beams, rafters, poles, furniture, window frames and beehives. Its durability in water makes it especially suitable for boat building, and in South Africa the logs are traditionally used to make the jetties and slipways around the swamps in the Kosi Bay area. The wood is also suitable for flooring, interior trim, joinery, toys, novelties, turnery, railway sleepers, mine props, veneer and plywood. It is popular as fuelwood and used for charcoal making. Smoke from burning wood is used to season milk containers.
The fruit is edible, but it has a rather bland taste. It is popular with children. The fruit is also made into jellies and alcoholic drinks. It yields a purple dye, whereas an orange or reddish brown dye is obtained from the bark. The tree is a host plant of the emperor moth (Micragone cana), of which the edible caterpillars are collected. The flowers provide nectar for honey bees.
In traditional medicine, a root decoction is drunk against amenorrhoea. Ash of the burnt wood is rubbed on the forehead against headache. Decoctions of the root bark and stem bark are taken for treatment of malaria. Root and bark infusions are taken to treat cough, root and bark decoctions to treat indigestion. The bark is used as an emetic and to treat diarrhoea, stomach problems, headache, amenorrhoea, wounds and respiratory problems. A leaf extract is drunk against cough, and an infusion of the leaves against diarrhoea and stomach complaints, and as a purgative. Ground leaves, bark and roots steeped in water are applied as a poultice as a galactagogue. The pulverized bark is sprinkled on water as fish poison.
Properties
The heartwood is red-brown or pink-brown to greyish, and not clearly demarcated from the sapwood. The grain is usually straight, sometimes wavy or interlocked, texture fine and even.
The wood is moderately heavy, with a density of 610–830 kg/m³ at 12% moisture content. Air-drying is slow, with a marked tendency to distort and split. The rates of shrinkage are high, from green to oven dry 4.0% radial and 10.1% tangential. Water-seasoning makes the wood more durable. The wood is moderately hard and moderately strong. At 12% moisture content, the modulus of rupture is about 75 N/mm², modulus of elasticity 7250 N/mm², compression parallel to grain 45 N/mm² and shear 14 N/mm².
The wood saws easily and works well with standard tools. Pre-boring is necessary for nailing; nail-holding properties are good. Moulding properties are good, and the wood planes to a smooth surface, taking a nice polish. It glues satisfactorily. The wood is recorded to be durable, particularly in water. In Zimbabwe it has been recorded to be resistant to termites. The sapwood is susceptible to Lyctus borers. The heartwood is very resistant to impregnation with preservatives, the sapwood moderately permeable. The wood is resistant to fire.
Methanol and water extracts of the bark have shown in-vitro antifungal activity against Candida albicans. Leaf extracts have shown in-vivo hypoglycaemic activity in rats. The bark and wood contain proanthocyanidins, pentacyclic triterpenoids, steroidal triterpenoids, ellagic acid and gallic acid. The anti-diarrhoeal properties of the bark may be due to the presence of phenolic compounds.
Botany
Evergreen shrub or small to medium-sized tree up to 20 m tall; bole up to 60 cm in diameter, seldom straight, often branched and gnarled, occasionally buttressed; bark surface rough, flaking or fissured, pale or dark brown; crown dense, spreading; branchlets 4-angled or slightly winged. Leaves opposite, clustered near the ends of branches, simple and entire; petiole up to 2.5(–5) mm long; blade oblong, oblong-elliptical, lanceolate-elliptical or almost round, 2.5–13.5 cm × 2–8 cm, base cordate and amplexicaul, rounded or broadly cuneate, apex rounded to acute or rarely short-acuminate or notched, blue-green above, paler green below, leathery. Inflorescence a terminal cyme up to 10 cm in diameter, many-flowered. Flowers bisexual, regular, usually 4-merous, white, pinkish or yellowish, fragrant; pedicel 1–3 mm long; calyx 6–9 mm long, with short lobes; petals united into a cap-like covering up to 3.5 mm × 6 mm; stamens numerous, 10–15 mm long, cream or white, conspicuous, fluffy; ovary inferior, 2-celled, style (5–)10–15 mm long. Fruit an oblong to nearly globose or urn-shaped berry 1–2 cm × (0.5–)1 cm, purple when ripe, tipped by the persistent calyx, usually 1-seeded.
Syzygium cordatum grows fast. In experiments in Malawi, trees were 2.7 m tall 27 months after planting. In southern Africa flowering is in August–November, and fruiting in November–March.
Syzygium is a large genus of about 1000 species, confined to the Old World tropics and subtropics, with the greatest diversity in South-East Asia. In the past it was included in Eugenia, which now mainly comprises species from the New World.
Within Syzygium cordatum 2 subspecies are distinguished:
– subsp. cordatum: shrub or small to medium-sized tree up to 20 m tall, young stems distinctly 4-angled or slightly winged, leaves distinctly cordate and amplexicaul at base; distributed from DR Congo eastward to Kenya and southward to Angola and South Africa, up to 2400 m altitude;
– subsp. shimbaense Verdc.: small tree up to 7 m tall, young stems mostly only scarcely quadrangular, leaves slightly cordate to rounded or broadly cuneate at base; distributed in Kenya and Tanzania.
Syzygium cordatum hybridizes with Syzygium guineense (Willd.) DC., and the 2 species are connected by a complete range of intermediates.
Ecology
Syzygium cordatum usually occurs in woodland and forest, nearly always near water or along watercourses, sometimes dominant in swamp forest, from sea-level up to 2400 m altitude. The average annual rainfall in the area of distribution is usually 750–1200 mm. The tree is resistant to fire.
Management
Seeds can be used for propagation. The 1000-seed weight is 2–2.5 kg. Seeds are recorded to retain viability for a day only, and should not be dried in the sun. Germination of fresh seed is good and rapid (90% in 25 days), and pretreatment is generally not considered necessary. In an experiment in Malawi, however, germination was 93% after soaking at room temperature for 24 hours, whereas various other treatments gave low or no germination. Seeds can be sown directly in the field or sown in pots in a nursery. Wildlings are sometimes planted out. Pollarding is possible. Stem and branch cankers have been observed, caused by Chrysoporthe austroafricana, an important pathogen of Eucalyptus spp. worldwide. Several Botryosphaeriaceae fungi cause cankers in Syzygium spp. as well as in Eucalyptus spp. Logs often split during felling, and heart rot may be present.
Genetic resources and breeding
Syzygium cordatum has a large distribution area and there are no indications that it is threatened by genetic erosion. It is protected in South Africa.
Prospects
The wood of Syzygium cordatum is strong, easy to work and very durable in water, making it particularly suitable for specific purposes such as boats and jetties. Because the bole is seldom of good shape, the commercial prospects are limited, unless straight-stemmed types can be selected.
Major references
• Bolza, E. & Keating, W.G., 1972. African timbers: the properties, uses and characteristics of 700 species. Division of Building Research, CSIRO, Melbourne, Australia. 710 pp.
• Katende, A.B., Birnie, A. & Tengnäs, B., 1995. Useful trees and shrubs for Uganda: identification, propagation and management for agricultural and pastoral communities. Technical Handbook 10. Regional Soil Conservation Unit, Nairobi, Kenya. 710 pp.
• van Wyk, B. & van Wyk, P., 1997. Field guide to trees of southern Africa. Struik Publishers, Cape Town, South Africa. 536 pp.
• Verdcourt, B., 2001. Myrtaceae. In: Beentje, H.J. (Editor). Flora of Tropical East Africa. A.A. Balkema, Rotterdam, Netherlands. 89 pp.
• Zambia Forest Department, 1979. Timbers of Zambia: Sclerocarya caffra, Syzygium cordatum. Zambia Forest Department, Division of Forest Products Research, Kitwe, Zambia. 4 pp.
Other references
• Chilufya, H. & Tengnäs, B., 1996. Agroforestry extension manual for northern Zambia. Regional Soil Conservation Unit, Nairobi, Kenya. 120 + 124 pp.
• Maghembe, J.A., Kwesiga, F., Ngulube, M., Prins, H. & Malaya, F.M., 1994. Domestication potential of indigenous fruit trees of the miombo woodlands of southern Africa. In: Leakey, R.R.B. & Newton, A.C. (Editors). Tropical trees: the potential for domestication and the rebuilding of forest resources. Proceedings of a conference held at Heriot-Watt University, Edinburgh, on 23–28 August 1992. HMSO, London, United Kingdom. pp. 220–229.
• Musabayane, C.T., Mahlalela, N., Shode, F.O. & Ojewole, J.A.O., 2005. Effects of Syzygium cordatum (Hochst.) [Myrtaceae] leaf extract on plasma glucose and hepatic glycogen in streptozotocin-induced diabetic rats. Journal of Ethnopharmacology 97(3): 485–490.
• Nakabonge, G., Roux, J., Gryzenhout, M. & Wingfield, M.J., 2006. Distribution of Chrysoporthe canker pathogens on Eucalyptus and Syzygium spp. in eastern and southern Africa. Plant Disease 90(6): 734–740.
• Neuwinger, H.D., 2000. African traditional medicine: a dictionary of plant use and applications. Medpharm Scientific, Stuttgart, Germany. 589 pp.
• Ssegawa, P. & Kasenene, J.M., 2007. Plants for malaria treatment in southern Uganda: traditional use, preference and ecological viability. Journal of Ethnobiology 27(1): 110–131.
• Steenkamp, V., Fernandes, A.C. & van Rensburg, C.E.J., 2007. Screening of Venda medicinal plants for antifungal activity against Candida albicans. South African Journal of Botany 73(2): 256–258.
• van Vuuren, N.J.J., Banks, C.H. & Stohr, H.P., 1978. Shrinkage and density of timbers used in the Republic of South Africa. Bulletin No 57. South African Forestry Research Institute, Pretoria, South Africa. 55 pp.
• van Wyk, B.E. & Gericke, N., 2000. People’s plants: a guide to useful plants of southern Africa. Briza Publications, Pretoria, South Africa. 351 pp.
• van Wyk, B.E., van Oudtshoorn, B. & Gericke, N., 1997. Medicinal plants of South Africa. Briza Publications, Pretoria, South Africa. 304 pp.
Author(s)
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands


Editors
D. Louppe
CIRAD, Département Environnements et Sociétés, Cirad es-dir, Campus international de Baillarguet, TA C-DIR / B (Bât. C, Bur. 113), 34398 Montpellier Cedex 5, France
A.A. Oteng-Amoako
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana
M. Brink
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
General editors
R.H.M.J. Lemmens
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
L.P.A. Oyen
PROTA Network Office Europe, Wageningen University, P.O. Box 341, 6700 AH Wageningen, Netherlands
J.R. Cobbinah
Forestry Research Institute of Ghana (FORIG), University P.O. Box 63, KNUST, Kumasi, Ghana

Correct citation of this article:
Brink, M., 2008. Syzygium cordatum Hochst. ex C.Krauss. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). Prota 7(1): Timbers/Bois d’œuvre 1. [CD-Rom]. PROTA, Wageningen, Netherlands.