Syzygium guineense (PROTA)
|Geographic coverage Africa|
|Geographic coverage World|
|Carbohydrate / starch|
|Dye / tannin|
|Forage / feed|
Syzygium guineense (Willd.) DC.
- Protologue: Prodr. 3: 259 (1828).
- Family: Myrtaceae
- Memecylon lopezianum A.Chev. (1917).
- Water berry, water pear, snake bean tree (En).
- Kisa d’eau (Fr).
- Mzuari, mzambarau, mzambarau mwitu, lubale, mkongoro, mlungiro (Sw).
Origin and geographic distribution
Syzygium guineense is one of the most widely distributed African trees, occurring from Senegal eastward to Somalia and southward to Namibia, Botswana and South Africa. It also occurs in Saudi Arabia and Yemen.
The wood is used for construction, flooring, panelling, furniture, utensils, tool handles, plates, stools, carvings and poles. Its flexibility makes it suitable for bows and ribs of canoes. The bole is made into dugout canoes. In East Africa the wood has been used for railway sleepers. It is also suitable for vehicle bodies, interior trim, joinery, toys, novelties, boxes, crates, mine props, veneer, plywood, hardboard and particle board. It is good fuelwood and used for charcoal making.
The fruit is edible. It has been described as sweet and juicy, but also as having a rather bland taste and not being appreciated. It is sought after especially by children, and in Ethiopia and Kenya the fruit is sold on markets. The fruit is made into a beverage, vinegar and added to spirits for flavouring. In Sudan a meal is made from roasted and ground fruits. The bark is used for tanning and dyeing. Bark extracts are sometimes used to harden lateritic floors or to glaze pottery. The leaves and fruits are used as fodder for livestock, and the flowers are a source of nectar for honey bees. The tree is used as a shade tree in coffee cultivation in Ethiopia.
Syzygium guineense finds wide application in African traditional medicine, but can be dangerous, as the bark may be poisonous, and death after its use has been recorded. The root is soaked in water for drinking and bathing to treat epilepsy. A root infusion is drunk for treatment of stomach-ache. Root extracts are taken as a purgative, anthelmintic and taeniacide. Bark decoctions are used against stomach-ache, diarrhoea and malaria; they are considered mildly laxative, and are applied in draught or in baths as a tonic. An infusion is taken against coughs, asthma, throat problems and intercostal pain. The powdered bark is used as an antispasmodic, purgative and anthelmintic, and used for treatment of diarrhoea, stomach-ache, broken bones and wounds. In Cameroon the bark is used for the treatment of snakebites. Twig bark preparations are applied against paralysis. A decoction of twigs and leaves is drunk or used as an enema for its purgative properties and against colic, diarrhoea and abdominal pain. It is also used as drink or bath against insanity, amenorrhoea and cerebral malaria. The crushed leaf is applied on wounds and boils, and taken to treat insanity and possession. Leaf decoctions are taken against intestinal parasites and stomach-ache, used as an enema against diarrhoea, and used as an embrocation to bathe and then massage into areas of sprain. Leaf decoctions or pulverized leaves are given as tonic to pregnant women. The leaf is chewed against stomach-ache. A liquid of chewed leaves mixed with water is used as eye drops to treat ophthalmia. The fruit is used for treating dysentery.
Production and international trade
No statistics are available on the production and trade of Syzygium guineense. The tree is of subsistence value in most parts of tropical Africa, the timber being traded locally, mainly for furniture production. The fruits are sold locally.
The heartwood is greyish red, brown or pink; it is not clearly demarcated from the 3–4 cm wide sapwood. The grain is straight, texture fine to medium. Growth rings are distinct. The wood is moderately heavy, with a density of 640–860 kg/m³ at 12% moisture content. Drying is slow, with moderate to severe distortion and splitting. In Tanzania boards of 2.5 cm thick air dry in 4 months and boards of 5 cm thick in 7 months. Kiln drying should be carried out at low temperatures; it gives a pronounced risk of distortion, and checking and splitting are fairly common. The rates of shrinkage from green to oven dry are high: 3.6–5.9% radial and 7.8–11.5% tangential. Movement in service can be large.
The wood is strong. At 12% moisture content, the modulus of rupture is 119–173 N/mm², compression parallel to grain 43–65 N/mm², shear 8 N/mm², cleavage 16–20 N/mm and Chalais-Meudon side hardness 3.0–4.7. The wood saws easily, but sawdust tends to adhere to the blades when the wood is fresh. It works easily with machine and hand tools, but is liable to splitting. It planes easily. Pre-boring is necessary for nailing; nail-holding properties are good. Moulding properties are good, and the wood bores and mortises well, when done with care. Reports on the durability of the wood vary, but it is frequently recorded as non-durable. The heartwood is extremely resistant to impregnation with preservatives, the sapwood is permeable.
Fruits collected in Malawi contained per 100 g dry matter: energy 1096 kJ (262 kcal), crude protein 10.1 g, fat 4.0 g, carbohydrate 48.5 g, fibre 30.3 g, Ca 23 mg, Mg 225 mg, P 30 mg, Fe 76 mg. They also contain ascorbic acid.
Extracts of the stem bark, leaves and seeds have shown antibacterial and antifungal activity, and methanol extracts of the stem bark molluscicidal activity. Triterpenes with antibacterial activity against Escherichia coli, Bacillus subtilis and Shigella sonnei were isolated from a methanol leaf extract, the most active being arjunolic acid and asiatic acid. A methanol extract of the bark inhibited contractions of rabbit ileum and produced hypotension in anaesthetized rats.
- Evergreen shrub or small to medium-sized tree up to 30(–40) m tall; bole branchless for up to 15 m, seldom of good shape, up to 150(–200) cm in diameter, sometimes with buttresses up to 1.8 m tall; bark surface smooth or with small rectangular flakes, grey or dark brown to almost black, inner bark pale brown to dark red-brown, sometimes with pink tinge or streaks; crown rounded and heavy; branchlets terete or 4-angled, sometimes drooping.
- Leaves opposite, simple and entire; petiole up to 2.5(–4.5) cm long; blade elliptical to oblong-elliptical or obovate-elliptical, (2.5–)4–16(–17.5) cm × 1–8 cm, cuneate at base, obtuse to acuminate at apex, leathery, shiny dark green above, pale green below, pinnately veined with many lateral veins, fragrant when crushed.
- Inflorescence a terminal cyme 5–19 cm long, many-flowered.
- Flowers bisexual, regular, 4-merous, white, fragrant, sessile; calyx with slender tube and small teeth, persistent; petals 2–3 mm long; stamens numerous, 4–8 mm long, white, showy; ovary inferior, 2-celled, style about as long as stamens.
- Fruit a globose to ellipsoid berry 0.5–3.5 cm × 0.6–2.5 cm, red to purplish black, tipped by the persistent calyx, usually 1-seeded.
- Seed rounded, yellowish to brownish.
Other botanical information
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.
Syzygium guineense is an extremely variable species with a complex taxonomy. It occurs in a wide range of vegetation types and shows a large variety of growth forms, ranging from a lofty forest tree with large plank buttresses to a rhizomatous undershrub. The flowers, however, are rather uniform and the fruits show only slight difference in shape. Variation in leaf shape and size seems to be continuous, and much of the variation appears to be closely correlated with ecology and habit. The taxonomic situation is further complicated by hybridization with Syzygium cordatum Hochst. ex C.Krauss and backcrossing with the parents. Primarily on the basis of the leaf shape, 11 subspecies have been recognized for Africa as a whole, the best-known being:
- subsp. guineense: tree up to 20 m tall, leaf apex obtuse to shortly acuminate, fruit up to 1 cm long; from Senegal eastward to Somalia and southward to Namibia, Botswana and South Africa, usually occurring in woodland;
- subsp. afromontanum F.White: tree up to 30 m tall, leaf apex distinctly acuminate, fruit up to 2.5 cm long; from Sudan and Ethiopia through East Africa and eastern DR Congo to Angola, Zambia, Malawi, Zimbabwe and Mozambique, usually growing in forest;
- subsp. huillense (Hiern) F.White: subshrub up to 60 cm tall, leaf apex acute to rounded or notched, fruit up to 3 cm long; DR Congo, Tanzania, Angola, Zambia, Zimbabwe, occurring in grassland;
- subsp. macrocarpum (Engl.) F.White: shrub or tree up to 12 m tall, leaves relatively large and broad, apex short-acuminate, fruit up to 4 cm long; from Gambia to Cameroon, Gabon, Central African Republic and DR Congo, in woodland and seasonally wet grassland.
The wood of various other Syzygium species is used.
Syzygium borbonicum J.Guého & A.J.Scott is endemic to Réunion, where it is known as ‘bois de pomme’, ‘bois de pomme blanc’, ‘bois de pêche marron’ or ‘bois à écorce blanche’. It is a buttressed tree up to 20 m tall. The wood is used in construction.
Syzygium cymosum (Lam.) DC. is endemic to Réunion and Mauritius, where it is known as ‘bois de pomme’ or ‘bois de pomme rouge’. It is a tree up to 20 m tall, with a bole diameter up to 50 cm. The wood is used for panels.
Syzygium micklethwaitii Verdc. (synonym: Syzygium sclerophyllum Brenan) is a shrub or tree up to 30 m tall, restricted to Kenya and Tanzania. The wood is used for mortars, tool handles, utensils and poles. The fruit is edible, and the tree also supplies fodder, shade and amenity.
Wood-anatomical description (IAWA hardwood codes):
- Growth rings: (1: growth ring boundaries distinct); (2: growth ring boundaries indistinct or absent).
- Vessels: 5: wood diffuse-porous; (12: solitary vessel outline angular); 13: simple perforation plates; 22: intervessel pits alternate; 23: shape of alternate pits polygonal; 26: intervessel pits medium (7–10 μm); 29: vestured pits; 31: vessel-ray pits with much reduced borders to apparently simple: pits rounded or angular; 32: vessel-ray pits with much reduced borders to apparently simple: pits horizontal (scalariform, gash-like) to vertical (palisade); 41: mean tangential diameter of vessel lumina 50–100 μm; 42: mean tangential diameter of vessel lumina 100–200 μm; 47: 5–20 vessels per square millimetre; (48: 20–40 vessels per square millimetre); 56: tyloses common.
- Tracheids and fibres: 61: fibres with simple to minutely bordered pits; 66: non-septate fibres present; 69: fibres thin- to thick-walled.
- Axial parenchyma: 76: axial parenchyma diffuse; 77: axial parenchyma diffuse-in-aggregates; 80: axial parenchyma aliform; 82: axial parenchyma winged-aliform; 83: axial parenchyma confluent; 93: eight (5–8) cells per parenchyma strand.
- Rays: 97: ray width 1–3 cells; (102: ray height > 1 mm); 108: body ray cells procumbent with over 4 rows of upright and/or square marginal cells; 109: rays with procumbent, square and upright cells mixed throughout the ray; 115: 4–12 rays per mm.
Growth and development
Pollination is by insects. Natural regeneration is adequate in natural forest.
Syzygium guineense occurs up to 2700 m altitude, in areas with an average temperature of 10–30°C and an average annual rainfall of 700–2300 mm. It is found in a wide range of vegetation types, including rainforest, montane forest, riverine forest and woodland. It prefers moist, well-drained soils with a high water table. The presence of the tree is considered a fairly good indication that the groundwater table is near the surface.
Propagation and planting
Propagation by seed is easy and is the commonly used method of propagation. The 1000-seed weight is 270–420 g. The seeds must be sown immediately after the fruits are picked, as they may spoil within 24 hours of storage. Germination is usually very good and uniform, and pretreatment of the seed is not necessary. Germination takes 20–30 days, with a germination rate of 80–90%. Seeds can be sown directly in the field or are sown in pots in a nursery. Wildlings can also be used for planting. Stem cuttings root easily, and grafting has been tested with a success rate of 50%.
The tree tolerates pollarding and is able to coppice.
Diseases and pests
Syzygium guineense is liable to attack by larvae of a Cerambycid beetle, which can make the timber defective. Heart rot is often present in larger trees. Stem and branch cankers have been observed, caused by Chrysoporthe austroafricana, an important pathogen of Eucalyptus spp. worldwide.
Ripe fruits are generally picked from the tree. If fallen, they must be picked immediately from the ground so that they do not spoil.
Since Syzygium guineense is widespread and rather common, it does not seem to be threatened. In countries where it is not common, such as Ghana, it may deserve some protection.
Syzygium guineense may have some prospects as a timber tree for local use in tropical Africa, as it is widely available and the wood is hard, strong, easy to work and suitable for a range of uses. Commercial prospects are limited, because the bole is seldom of good shape. The variability within the species can be used for selection and cloning of superior genotypes. More detailed knowledge of selection and standardized vegetative propagation methods are the main prerequisites for a breakthrough in productivity. Although the tree is widely used in traditional medicine, caution is needed as death has occurred after use of the bark. Research on the phytochemistry is warranted.
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Sources of illustration
- Akoègninou, A., van der Burg, W.J. & van der Maesen, L.J.G. (Editors), 2006. Flore analytique du Bénin. Backhuys Publishers, Leiden, Netherlands. 1034 pp.
- A. Maroyi, Department of Biological Sciences, Bindura University of Science Education, P.B. 1020, Bindura, Zimbabwe
Correct citation of this article
Maroyi, A., 2008. Syzygium guineense (Willd.) DC. In: Louppe, D., Oteng-Amoako, A.A. & Brink, M. (Editors). PROTA (Plant Resources of Tropical Africa / Ressources végétales de l’Afrique tropicale), Wageningen, Netherlands. Accessed 8 July 2021.
- See the Prota4U database.