Wahlenbergia nodosa, in Afrikaans the muistepelkaroo (mouse nipple Karoo), is a rigid, somewhat spiny-leaved shrublet reaching 60 cm in height. The common name was probably given based upon the shape of the flower buds. Nodosa means knotty in Latin, probably referring to the leaf distribution upon the stems.
The distribution of the species is wide, from the Cape Peninsula to eastern parts of the Northern Cape, parts of the Eastern Cape and into the southern Free State. The plant grows in loam soils on dry rocky slopes and flats among various vegetation types. The species is not considered threatened in habitat early in the twenty first century (Vlok and Schutte-Vlok, 2010; iSpot; Bond and Goldblatt, 1984).