Romulea sulphurea

Manning, John C. & Goldblatt, Peter, 2001, the Arabian Peninsula and Socotra including new species, biological notes, and a new infrageneric classification, Adansonia (3) 23 (1), pp. 59-108 : 70

18. Filaments at least twice as long as the anthers; flowers golden- or orange-yellow .............. 24. R. sulphurea

18’. Filaments less than twice as long as the anthers, mostly more or less equal in length; flowers bright or pale yellow .................................................................................................................................................... 19