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 alba, commonly known as White Oneye, is a South African endemic annual found growing in the Eastern Cape and Western Cape provinces. From early spring, through to late summer it produces striking white to purple flowers.