The genus Nymphaea consists of roughly 40 species found in tropical and temperate climates of both hemispheres. It is full of synonymy, because different populations or colour forms have been described as separate species which have since been sunk into one species and in some cases the same plants have been described as different species by different botanists, or the name of one species has been misapplied to another species. It all gets rather confusing. There are also many variants and hundreds of hybrids that come in all colours, shapes and sizes.
There are only two species that occur in southern Africa. One is Nymphaea lotus, the white water lily, or white lotus which has night-blooming white or cream flowers and is widespread in tropical Africa to southern Africa, where it occurs in the former Transvaal, KwaZulu-Natal, Botswana, Swaziland and Namibia, and in Madagascar, in sheltered water 0.5-2.5m deep and in swamps. It also occurs in hot springs in Hungary and Romania. There is a variety in Australia and it is widely cultivated in the USA and South America.
The other southern African species isNymphaea nouchali. The blue lotus, Nymphaea caerulea and the Cape blue water lily, Nymphaea capensis are no longer regarded as distinct species and have been sunk into this genus.
The type specimen was collected in Coromandel in India. The meaning of the specific ephithet nouchali has only been traced with the assistance of staff at Kew who report that one of their specimens contains a note that Noakhali is a district in Bangladesh. The variety name caerulea refers to the sky blue colour of the flowers.