Common Names: Knob Thorn, Muzalazambe, Mukwena, Mkunku, Mwaba
Family: Fabaceae (Pea Family) Mimusoideae
 
Growth Form, Habitat and Distribution 
A medium to large deciduous tree of open savanna, or Munga woodland with a rounded or spreading crown, named for its knob like thorns on the trunk and branches. Widespread at low and medium altitudes, except in northern Zambia.
Size     Height 10 to 20m, spread 6 to 12m.
Bark    Dark brown to black, fissured and ridged with conspicuous knobs tipped by small, paired, hooked prickles.
Leaves    Alternate and bipinnate with 1 to 4 pairs of pinnae, each with 1 or 2 pairs of large (1.5 to 2.5cm),  grey-green leathery oval to circular leaflets. Often leafless for several months.
Flowers    Fragrant, white clustered spikes, usually appearing before new leaves, August to November.
Fruit     Thin, straight, red-brown, dehiscent pods up to 16cm, tapering to the stem, January to June. Pods explode 2 to 6 green-brown seeds with horse marking, July to September.
Uses    The flowers attract bees. The leaves and fruits are protein-rich and eaten by domestic animals and wildlife. The bark makes a good rope. Senegalia nigrescens has attractive flowers and is drought resistant. This makes a good garden specimen tree if planted in groups of 3 or 5, but does drop thorny stems. It has a non-aggressive root system. 
Other species in Zambia: 28 other Acacia species and 8 sub-species.