It can tolerate the roots being in anoxic mud in nutritionally poor conditions, and can become a dominant plant in deeper water in such habitats.

Though it is still most commonly referred to as a variety of Nymphaea nouchali, recent phylogenetic studies have problematized the taxonomy.

The upper surface of the lamina is smooth, but the underside has conspicuously raised, green or rarely reddish or reddish-purple veins.

The primary veins form a pattern of closed, elongated areas stretching to more than two thirds of the way to the margin of the leaf.

[12] The flower buds rise to the surface over a period of two to three days, and when ready, open during the mid-morning, closing near dusk.

[6] In the 1970s and 1980s William Emboden suggested that Nymphaea caerulea contained aporphine alkaloids (though photochemical studies were not performed); more recent photochemical analysis did not find aporohine alkaloids and the chemical composition of Nymphaea caerulea was discovered to include compounds such as 7-hydroxyflavone, 4,7-dihydroxyaurone, and 4’-hydroxyaurone, along with methyl vanillate and cinnamyl alcohol.

[14] Nymphaea spectabilis, a purple form known from cultivation, and N. capensis, found throughout eastern, central and southern Africa, as well as a number of other named taxa, were synonymised to N. nouchali var.

caerulea in the 1989 addition to the Flora of Tropical East Africa (FTEA) series, a position which has generally been accepted,[1][4][15][16] although some of the authorities in Bangladesh[16] and in the United States disagree.

[17] When genomes from the water lily genus (Nymphaea) were published in the journal Nature in 2020, N. caerulea was cited under that name, not as N. nouchali var.

[18] Another phylogenetic study from 2021 found N. caerulea (as N. capensis) to be closest related to N. colorata, an east African species.

[19] Nymphaea nouchali is itself a taxonomically challenging species, with a distribution that spans Australia, throughout southern Asia,[20] across Africa to the Western Cape.

[5] On the African continent, it occurs, from north to south, westwards to at least Chad,[1][22] Congo-Brazzaville,[1] the DRC (only in Katanga?

[1][22] In South Africa this plant is found in every province, as well as in eSwatini, but it is not native to Lesotho and the Western Cape.

[10] It is native to Yemen[1][2] and Oman (in Dhofar) in the southern Arabian Peninsula[1] but, according to Moshe Agami in a 1980 paper, is thought to have become extinct in the wild in Israel.

[2] It has more recently been spread more widely around the world as an ornamental plant, and introduced populations are now found in Bangladesh,[1][3] Meghalaya, Kerala[6] and Assam in India,[1][6] Fiji, Mauritius, North Island in New Zealand, New South Wales and Queensland in Australia, Cook Islands, Costa Rica,[1] and throughout eastern South America (in Brazil and Argentina).

[26][27] The waterlily stands in this lake are especially poor in invertebrate biodiversity, which may reflect the low levels of dissolved oxygen near the sediments in this habitat.

[28] In Lake Bisina, Uganda, N. caerulea is most clearly associated with Utricularia reflexa; this may be due to similar ecological niches, it may just mean the small, rootless, free-moving Utricularia simply get snagged on the petioles, but it may indicate some sort of a commensal relationship, with U. reflexa being shaded by the leaves of N. caerulea.

[30] In fact, the carpellary appendages in this type of water-lily appear to have evolved specifically to attract bee species in general.

In colder climates, the plants lose their leaves and go dormant during the winter, with the rhizomes remaining alive below the water.

[4] Gomphonema gracile is an epiphytic diatom found on N. caerulea in high elevation Lake Naivasha, Kenya.

[32] In Kenya, N. caerulea is positively associated with the freshwater snail Biomphalaria pfeifferi, which is a main host of human schistosomiasis.

[4] It has been suggested that it was used in ancient Egypt for religious rituals and sexual enhancement, due to the purported presence of apomorphine, which is also used today to treat erectile dysfunction.

[citation needed] According to a multimodal analytical study, traces of Peganum harmala, and Nymphaea nouchali var.

[36] Blue Lotus (Nymphaea caerulea) is a plant known for its relaxing properties and historical significance in ancient Egyptian culture.

[21] The Longwood Gardens in Kennett Square, Pennsylvania has had Nymphaea caerulea in their water lilly collection[38] since 1963.

They have been depicted in numerous stone carvings and paintings, including the walls of the temple of Karnak, and may be associated with rites pertaining to the afterlife.

[4] N. caerulea was considered extremely significant in Egyptian mythology, regarded as a symbol of the sun, since the flowers are closed at night and open again in the morning.

At Heliopolis, the origin of the world was taught to have been when the sun god Ra emerged from a lotus flower growing in "primordial waters".

[45] N. caerulea has been illegal in Russia since April 2009, along with related products such as Salvia divinorum, Argyreia nervosa, and others.