Vachellia gerrardii subsp. gerrardii rough bark

The stem of Vachellia gerrardii subsp. gerrardii has dark grey bark that may be either smooth or rough. The tree usually has a single stem that branches low down; big trees may have trunks measuring 35 cm in diameter near the base. Bark on the tree in picture is rough and grey with fissuring and some flaking. Red colouring sometimes shows in the fissures. This brings the species the common name of red thorn.

Young branches have grey, velvety hairs. The upper bark on young stems may also peel or split to expose rusty red underbark. Some transverse wrinkling of the bark is found on the young branches. Growing tips are hairy, grey-green or pinkish and showing lenticels on the stems.

The spines or thorns are usually straight and short, commonly around 1 cm in length, although some of up to 6 cm with variable backwards curvature also occur. Thorns are white with dark tips and hairy when young. They grow in pairs at the nodes that are spaced up to 2 cm apart on the stems (Coates Palgrave, 2002; Carr, 1976).