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 kowynensis, commonly known as Longtom Oneye, is a South African endemic perennial found growing in the Mpumalanga province from Mariepskop to Graskop and the Long Tom Pass growing along forest margins in mistbelt grassland. From late spring, through to early autumn it produces dainty blue and purple flowers.