Agroforestree Database

Local names:
 Afrikaans (ysterhout), English (ironwood olive,ironwood,Elgon olive,East African olive,black ironwood), Swahili (mushargi,loliondo), Trade name (olive,mutharagi,mutharage,loliondo)

Olea capensis is often a bushy shrub or a small to medium sized tree up to 10 m in height, but it may be much larger, occasionally reaching 40 m; occurring in bush, littoral scrub and evergreen forest. Bark: light grey, becoming dark grey and vertically fissured with age; a characteristic blackish gum is exuded from bark wounds. 

Leaves lanceolate-oblong to almost circular, 3-10 x 1.5-5 cm, light to dark green and glossy above, rather paler green below, although sometimes almost unicoloured, occasionally purplish-tinged, without hairs or scales; apex broadly tapering to almost rounded; base tapering; margin entire, thickened and often very wavy; petiole often purplish, 0.3-1.7 cm long.

The flowers are small, white or cream, sweetly scented, in many flowered axillary or terminal heads, 3-15 cm long. 

Fruit ovoid, fleshy, up to 2 x 1 cm, when ripe they are somewhat succulent purplish drupes. 

This species has been divided into 3 subspecies: ssp. macrocarpa, fruits oblong to elliptic, up to 2 x 1 cm; flowers in lax heads. Ssp. capensis, fruits almost spherical to oblong elliptic, up to 1 cm long; flowers in dense heads and leaves very variable, apex often rounded; branchlets grey to greyish-brown. Ssp. enervis, leaves usually broadly elliptic, apex tapering; branchlets grey to whitish.

Ecology

O. capensis occurs almost throughout Africa south of the Sahara desert from Sudan and Ethiopia to the southern extremity of the continent and west to the Islands of the Gulf of Guinea and to Sierra Leone. A species of situations where temperatures are relatively low and, apart from diurnal fluctuations, fairly constant temperatures throughout the year. In East Africa, the elevations where the tree naturally grows provide these conditions, and further south in the range it occurs at lower elevations but at these latitudes temperatures are also lower. O. capensis ssp. macrocarpa is well known in its indigenous range of southern Africa.

Native range
Angola, Botswana, Cameroon, Central African Republic, Congo, Democratic Republic of Congo, Djibouti, Equatorial Guinea, Eritrea, Ethiopia, Gabon, Kenya, Lesotho, Madagascar, Malawi, Mozambique, Namibia, Rwanda, Sao Tome et Principe, Sierra Leone, Somalia, South Africa, Sudan, Swaziland, Tanzania, Uganda, Zambia, Zimbabwe

Tree management

Growth is reported fast in young plants but much slower in older ones. Over the first 4 years a mean annual height of 1.1 m has been reported. It is a shade-tolerant, pioneer species and a dominant forest tree. Protected from uncontrolled harvesting in Tanzania.

Seed storage behaviour appears to be orthodox. Storage of the seed is not advisable without refrigeration facilities: if these are available a low temperature 3 deg. C should be used. There are 3 000-3 300 seeds/kg.

O. capensis occurs almost throughout Africa south of the Sahara desert from Sudan and Ethiopia to the southern extremity of the continent and west to the Islands of the Gulf of Guinea and to Sierra Leone. A species of situations where temperatures are relatively low and, apart from diurnal fluctuations, fairly constant temperatures throughout the year. In East Africa, the elevations where the tree naturally grows provide these conditions, and further south in the range it occurs at lower elevations but at these latitudes temperatures are also lower. O. capensis ssp. macrocarpa is well known in its indigenous range of southern Africa.

O. capensis is usually raised from seeds. Seed is collected and cleaned of all pulp, soaking in water for 2 days makes removal easier. Dormancy is a major problem. Fresh, mature, healthy seed germinate reasonably. Germination percentage tends to be low (30-40%) and uneven (usually extended over 2-3 months but even occurring as late as 2 years after sowing).

O. capensis is a useful fodder tree.

A viable species for fuelwood from which excellent charcoal can be made.

Timber:  The wood of ssp. capensis and ssp. enervis is rarely used, but that of ssp. macrocarpa makes a fine, high quality timber. It has dark brown heartwood and is attractively figured, fine-grained, hard and heavy and although it is difficult to work it has been widely used in railway sleepers, wagon woods, bridge construction and for flooring blocks. It can also produce beautiful furniture.