Caesalpinia rostrata, in Afrikaans known as kaalrug (bare back), is a woody shrub reaching 3 m in height. The main stem is armed with hooked thorns that are up to 1 cm long. The plant in picture is multi-stemmed, photographed in Mjejane Game Reserve where it is rare.

The plant bears pink flowers in terminal and axillary racemes. The flowers are shaped like pea flowers, the calyces five-lobed. Caesalpinia flowers have ten stamens that are free from each other. The flowers are popular with bees and other insects. They are produced from late spring to midsummer.

The fruit pods are short, about 3 cm long and inflated, tipped by a distinctive beak-shape. The specific name rostrata means beaked, referring to this pod-shape.

The species distribution is restricted to a part of the Mpumalanga Lowveld and probably southern Mozambique.

The habitat is granitic bushveld and basalt Lowveld, often along rivers and drainage lines. The species is considered to be rare and vulnerable in its habitat early in the twenty first century. Its population is decreasing from habitat destruction caused by farming (Schmidt, et al, 2002; Leistner, (Ed.), 2000; iNaturalist; http://pza.sanbi.org; http://redlist.sanbi.org).