Selago aspera is an erect shrublet that grows up to 30 cm. The plant is much-branched, the branches furry with hair. Several species within the Selago genus are known as bitterbushes.
The flowers are pale mauve or white on short stalks in dense spikes or clusters at stem tops. The calyx is cup-shaped and five-lobed. The corolla is funnel-shaped, five petal lobes opening wide at the mouth. There are two pairs of stamens in the flower, some protruding from the mouth, as does the stigma.
The species distribution is in the Western Cape from Bredasdorp and Worcester to the Little Karoo.
The habitat is lower fynbos slopes on sandstone, as well as limestone soils. The species is not considered threatened in habitat early in the twenty first century (Bond and Goldblatt, 1984; Mustart, et al, 1997; http://redlist.sanbi.org).