Common names
Knobwood (English); chipolo, pupwe, pupwe-chulu (Bemba); mchodzi, mulunguchulu (Nyanja).
General description and distinguishing characteristics
A small tree up to 6 m tall, characterised by knobs with spines up to 1.5 cm long on the bole and branches. Bark pale grey and smooth except for the knob-like thorns. Leaves alternate, compound, imparipinnate, up to 22 cm long with up to 5 pairs of ovate, oblong or obovate-oblong leaflets up to 6.5 x 3.5 cm. Leaf rhachis with small hooked thorns along its length. Leaflet margins toothed, and leaflets sparsely dotted with glands. Leaflets give off a citrus smell when crushed. Petiole 1-5 cm long. Flowers small, greenish, produced below the leaves in sprays or racemes 5-10 cm long (November-March). Fruit spherical, up to 5 mm in diameter, red-brown when mature, splitting to reveal a black seed (fruits produced February-May).
Range and habitat
Zanthoxylum chalybeum is distributed throughout south-central and eastern Africa. In the Luangwa valley and elsewhere it is typically found on termite mounds.