Researchers at the University of Koblenz rediscover the world's smallest water lily in Rwanda, which was declared extinct

Nymphaea thermarumwhich is the scientific name for the water lily and whose flower is no larger than the size of a one cent piece, is a local endemic, i.e. a species that only grows naturally in such spring creeks worldwide - in an area smaller than a football field. Since its discovery, this plant has therefore been considered extremely endangered, as nearby agriculture and mining have severely restricted its habitat. For this reason, a few specimens of the plant were cultivated in botanical gardens around the world in the early 1990s to help preserve the species outside its natural habitat.

Increasingly intensive agriculture and the expansion of the mining area led to the disappearance of the water lily species in the wild. It was last seen in its natural habitat in 2008, but was declared extinct in nature by the International Union for Conservation of Nature (IUCN) in 2010. Once again, inappropriate land use, coupled with a lack of knowledge about rare species, had led to the extinction of a species in the wild.

From then on, the species survived in water tanks and aquariums in at least a dozen botanical gardens around the world. Ideas and studies for reintroduction into the wild were developed. With the intention of surveying the original site for such a project, Sarah Marie Müller and Siegmar Seidel from the Rwanda Centre and Office for Africa Cooperation at the University of Koblenz travelled to Rwanda in July / August 2023 together with Prof. Dr Thomas Abeli from the Italian University of Roma3 and discovered a new or surviving population of the world's smallest water lily not far from the original site. The question of how this was possible is now being investigated in a research project.

Prof Dr Eberhard Fischer, who first discovered it, is also delighted about its rediscovery: "I am very pleased about the rediscovery ofNymphaea thermarumThis can certainly be considered a sensation. It is also my first new discovery in Rwanda, which I made in 1987 and published in 1988.Nymphaea thermarum is one of the rarest plants in the world".

There is also enthusiasm in Rwanda, where Siegmar Seidel personally presented the good news to the responsible ministers. The Ministry of the Environment, the Ministry of the Interior and their subordinate authorities now want to designate the habitat of the world's smallest water lily as a protected area. "The work now begins for our Koblenz-Roman team, as there is still a lot of research to be done on the plant. We also want to incorporate the previous research work of other colleagues from other universities and botanical gardens around the world," explains Siegmar Seidel, who will be travelling to Rwanda again this week.

The rediscovery of theNymphaea thermarum has now been published in the Oryx Journal: Abeli, T., Müller, S. M. and Seidel, S. (2024) 'Rediscovery of the waterlily Nymphaea thermarum Eb. Fisch. in Rwanda',Oryx, pp. 1-3. doi: 10.1017/S0030605323001837.