Acacia mellifera (Vahl) Benth.

Acacia mellifera is a low, branched tree with a more or less spherical crown. Black bark on stem becomes ash-grey to light brown on the branches, bearing small, short, sharply hooked spines in pairs. It has a shallow but extensive root system radiating from the crown, allowing the plant to exploit soil moisture and nutrients from a large volume of soil. The roots rarely penetrate more than 1 m. Leaves characterized by 2 pairs of pinnulae, each with a single pair of leaflets. Leaflets elliptic 0.6-2 cm long and 0.6-1.2 cm wide, glabrous and highly coloured beneath. Flowers sweetly scented, especially at night, in elongated spikes, cream to white in spiciform racemes, up to 3.5 cm long; pedicels 0.5-1.5 mm long; calyx up to 1 mm long; corolla 2.5-3.5 mm long. The papery pods with 2-3-seeds are reticulate, flat, elongated, 2.5-5.5 cm long, 6 cm wide, hemmed, sometimes more or less narrowed between the seeds. The generic name ‘acacia’ comes from the Greek word ‘akis’, meaning point or barb. The specific name means ‘honey-bearing’.

Flowering and fruiting start 3 years after planting and generally occur twice a year. Flowers are borne on shoots produced the previous year, that is, old wood. The flowers open and shed before the leaves appear. In southern Africa, flowering occurs from September to November and fruiting from January to April.

A. mellifera is normally found on hard-surfaced, sandy soils and rocky hillsides. It grows well in black cotton soils but prefers loamy soils.

A. mellifera is a commonly occurring shrub on rangelands throughout the savannah in western, eastern and southern Africa. The terrain preference is rocky hillsides with rainfall along seasonal watercourses, mixed with other trees. If left unattended, especially if grazing is heavy and no fires check its spread, it may form dense, impenetrable thickets, 2-3 m high and sometimes hundreds of metres across, slowly taking over good grazing land. This species is drought-tolerant.

Direct sowing of seeds is the common method of artificial propagation. Seed are soaked in concentrated sulphuric acid for 5-15 min or in hot water, left overnight and planted the next morning. Seeds usually germinate from the 5th day onwards. Due to its high rate of seeding, long viability of seed and ability to overcome arid climates, profuse natural regeneration is generally common.

Young trees are subject to heavy browsing by stock and game and must be protected for the first two seasons. A. mellifera has a moderate growth rate of up to 500 mm/year. It does not coppice well.

Seed storage behaviour is orthodox; viability can be maintained for several years in hermetic storage at 10 deg. C with 4.5-9% mc. There are approximately 20 000 seeds/kg.

Shade or shelter: When pruned regularly, A. mellifera in arid areas provides animals with shade from the hot sun. Boundary or barrier or support: Makes a good live fence and hedge. Intercropping: A. mellifera has an aggressive root system, limiting its use in farms with crops.

Food: Gum collected from injured stems is edible and relished by children, animals and birds. Fodder: Camels and goats browse the leaves, which are rich in protein, taking them from the shrubs or from the ground. Apiculture: The cream/white flowers produce excellent quality honey (‘mellifera’ = producing honey). Bees forage in the late morning to mid afternoon when hot and dry. The honey is water colour and granulates slowly. Fuel: The wood is used for fuel and charcoal. Timber: The wood is taken for building huts and the branches for fencing. Poison: The poison with which Bushmen tip their arrows is often made from a powdered grub mixed with the sap of A. mellifera. Medicine: The bark decoction is used for stomach-ache, sterility, pneumonia, malaria and syphilis. In Botswana, a decoction of the roots is a medicine for stomach pain. Other products: In Sudan, baskets made of the roots serve for collecting gum arabic. The bast fibres are used for wickerwork.