Nymphaea thermarum is known as the smallest waterlilies. Dr. Eberhard Fischer, the German botanist, discovered Nymphaea thermarum on the edges of the hot spring, in Mashyuza, Rwanda, in 1987. He, therefore, named it them arum. The spring was later diverted and dried up and his samples helped continue the survival of the species. Thought this is the only species of water lily that can grow in mud rather than water.
The flowers have both male and female phases. The first flower blooms it is female and secretes a droplet to cover its stigma. Therefore, insects can carry pollen that gets caught in the droplet later falling into the stigma. At night the flower closes and the droplets disappear, the next day the flower acts as the male and releases pollen.
Nymphaea thermarum is in cultivation at Kew Gardens in the UK where these photographs are from as well as in Germany. It is propagated by seed. The seeds usually require CO2 to germinate it was not until Carlos Magdalena of Kew Gardens discovered this and grew the plants in pots of loam surrounded by water.
It generally forms rosettes of 30cm or 12 in wide. The leaves or lily pads are bright green. The flowers are white and have yellow stamens. They grow a few centimeters above the plant.
Also, read about other rare waterlilies at Kew Gardens: Nymphaea ‘Kew’s Stowaway Blues’