Chiabaca salutaris Bertol. f.

Warburgia salutaris is an aromatic evergreen tree, usually 5-10 m in height, but reaching 20 m in some areas, with a dense erect canopy. Bark smooth and grey on young branches but brown and slightly rough with prominent yellowish corky lenticels on older branches and stems; inner bark reddish, with a peppery smell. Leaves aromatic, alternate, simple, elliptic to lanceolate, 4.5-11 x 1-3 cm, glossy dark green above, paler green and dull below; midrib frequently slightly off-centre; apex and base tapering; margin entire; petiole 1-3 mm long. Flowers bisexual, up to 7 mm in diameter, solitary or in 3-flowered cymes in axils of leaves, green, 3 sepals, 10 petals, 5 inner petals smaller, thinner in texture and yellower than outer 5, filaments fused to form a prominent staminal tube. Fruit oval berries, 4 cm in diameter, turning dark purple when ripe; skin leathery, glandular, black when mature. Containing 2 or more seeds with oily endosperm. The genus is named after Dr Otto Warburg (1859-1938), born in Hamburg, a lecturer in botany at the University of Berlin and author of numerous botanical papers. The specific name ‘salutaris’ means ‘healthy’ or ‘salutary’, presumably in reference to its medicinal properties.

Insects pollinate the bisexual flowers and birds disperse the fruit. In South Africa, flowering time is from April to May and fruiting from October to January.

Habitat ranges from evergreen montane forest to evergreen sandveld forest along the coast; also found in secondary bushland, wooded ravines and in grasslands. It is moderately drought resistant and not suitable for areas that experience frost.

W. salutaris has been an article of trade since the 1st Arab dhows traded with northeast Africa. It is a most popular medicinal tree, having been used in Africa for centuries. The constant demand for the bark, especially the root bark, has led to large-scale destruction of natural populations, to the extent that many have been wiped out.

W. salutaris can be grown from seed, but the seeds are invariably infested with insects. Wash the fruit first and sow fresh seed promptly; germination rates are good (over 80% in about 15 days). An easier and more successful method is to grow the plant from root suckers or, better still, from stem and tip cuttings. When sufficient roots are formed, transfer the plants into nursery bags filled with a mixture of river sand and compost (3:1) and keep them for a year before planting out. The tree also has been successfully propagated using wildings.

The tree has coppicing abilities. Care and good time management must be taken during bark removal to avoid tree mortality. The tree can be planted along fence lines, in scattered groups or, preferably, in a small plantation. Although fairly slow growing, in warm, frost-free areas growth can be as much as 90 cm/year.

W. salutaris is classified as recalcitrant; however, with dry seed viability can be maintained for 6 months at cool temperatures; storability is intermediate between orthodox and recalcitrant. Seed can be stored for a short time in moist sawdust at 3 deg. C. More investigation is needed. There are approximately 10 500 seeds/kg.

Shade or shelter: The dense leaf canopy provides good shade. Soil improver: Foliage can be used for green manure and mulch. Ornamental: An evergreen tree with white flowers, W. salutaris is widely planted as an ornamental. When used as greenery in flower arrangements, small branches last up to 3 weeks in water. It is also very successful when grown as a pot plant; if kept in light shade the plant takes on a neat shape and the leaves become very glossy. Boundary or barrier or support: It can be grown either as single trees around boundaries or to make an attractive dense hedge. Intercropping: W. salutaris can be intercropped for shade in coffee, banana and cocoa plantations.

Food: Fresh or dried leaves can be used in various dishes or tea to add an agreeable aroma and, peppery taste. Fodder: Leaves, pods and seeds all provide good fodder. Fuel: Wood is used as firewood and charcoal. Timber: Sapwood light yellow, heartwood dark yellowish-brown, oily, aromatic and darkening with exposure to air. The wood is used as a timber for furniture and tools. It saws and planes well but it is not durable. Gum or resin: Resin is extracted from this tree; the peppery taste is due to the amorphous resinous substances. Tannin or dyestuff: Tannins are found in the bark. Medicine: The inner bark is used as a treatment for malaria, colds, chest complaints, coughs, diarrhoea, muscle pains, stomach-ache and general body pains. Dried and ground to a snuff, it is used to clear the sinuses; smoke from the burning bark is inhaled as a remedy for chest complaints. The stem and root bark act as an expectorant; the leaves are used as part of an infusion to treat rheumatism. Other products: The bark contains mannitol.