The Monopsis genus consists of 16 species, all of which are indigenous to South Africa where they can be found from Namaqualand to the southern Cape, east to KwaZulu-Natal and north to Limpopo.

Monopsis acrodon, synonymously known as Monopsis acrodon var. herois and commonly known as Cederberg Oneye, is a South African endemic annual found growing in the Western Cape province. From late spring, through to summer it produces eye-catching yellow flowers.