Risking his own extinction to rescue the rarest of flowers

LONDON — In Australia, he went plant hunting by helicopter and waded in crocodile-infested waters to watch a water lily bloom. In Mauritius, he grabbed a plant specimen off the ledge of a cliff. Last month, while looking for lilies in a tributary of Colombia’s piranha-packed Orinoco River, he jumped from plank to plank in the pitch dark at 4 a.m. to get to a floating pontoon. “It’s not that I am that daring,” said Carlos Magdalena, a research horticulturalist at the Royal Botanic Gardens, Kew, in London. “These situations...