Seed morphology of 6 species ofNigella L. (Ranunculaceae) viz.,N. sativa L.,N. hispanica L.,N. arvensis L.,N. orientalis L.,N. nigellastrum (L) Willk. andN. integrifolia Regel, was studied utilising the light and scanning electron microscope to determine the significance of testa features as taxonomic characters. An artificial key based on spermoderm features is proposed to delimit the species studied. The present study supports the treatment ofN. integrifolia Regel as a monotypic genusKomaroffia integrifolia (Regel) Periera.