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 just arise, and they are not like Superman extreme. Sometimes it’s more Peter Sellers than Indiana Jones.”

Mr. Magdalena’s main responsibility at Kew Gardens is tending tropical plants. But he is also known as “the plant messiah,” as anointed by a Spanish newspaper in 2010, for his work rescuing several plant species from the brink of extinction. That work has earned him enormous respect in the field of botany and made him somewhat of a celebrity in the horticulture world.

His renown only grew when David Attenborough, the British doyen of nature documentaries, repeated the “plant messiah” tagline at the 2012 premiere of one of his films, which featured a scene of Mr. Magdalena propagating the pygmy lily.

The attention, especially from a figure as venerated as Mr. Attenborough, initially dismayed Mr. Magdalena. “Imagine what happens when the God calls you the messiah,” he said, standing outside one of the graceful greenhouses at Kew Gardens.

It is appropriate that Mr. Magdalena’s star moment in the documentary showed him working with lilies, the plant closest to his heart and the first one he grew as an 8-year-old on his parent’s finca, a plot of land in the Asturias region of northern Spain.