The Nymphaea thermarum has pads that are only 1cm in diameter.
It became extinct in its native Rwanda and there were only two plants and a few seeds in existence. Attempts to grow the plant failed and after one of the two remaining specimens was eaten by a rat, its fate appeared to be sealed.
But Kew horticulturist Carlos Magdalena realised that it should be grown in mud rather than water. "Now that we know how to do it, it seems easy," he said.
Magdalena now has around 25 plants and 70 seedlings. He said the plant was suitable for commercial production but this would require permission from the Rwandan government.
The plant could be hybridised with other lilies and it might be possible to produce offspring with different colours, he suggested.