Wahlenbergia nodosa, in Afrikaans the muistepelkaroo (mouse nipple Karoo) and previously scientifically Lightfootia nodosa, is a rigid, somewhat spiny-leaved shrublet reaching heights from 15 cm to 60 cm.
The common name was probably given based upon the oblong shape of the flower buds and the plant's prevalence in the Karoo. Nodosa means knotty in Latin, probably referring to the leaf distribution upon the stems.
The distribution of the species is wide-ranging, from the Cape Peninsula across the Western Cape to the eastern parts of the Northern Cape and the southwest of the Free State in the centre of the country, as well as the west of the Eastern Cape.
The plant grows in loam soils on dry rocky slopes and flats among various vegetation types. The species is not considered to be threatened in its habitat early in the twenty first century (Vlok and Schutte-Vlok, 2015; Bond and Goldblatt, 1984; iSpot; http://redlist.sanbi.org).