Great Britain

Dead rats, putrid flesh and sweaty socks: rare orchid gives UK botanists their first whiff

It is famous for smelling like “a thousand dead elephants rotting in the sun”, its petals resemble decaying flesh, and it is so rare that outside its natural habitat in Papua New Guinea, few botanists in the world have ever seen it in flower.

Now this highly pungent orchid – Bulbophyllum phalaenopsis – is in bloom for the first time in a glasshouse at Cambridge University Botanic Garden.

“It’s such an unusual plant,” said head of horticulture Sally Petitt. “The reasons we cultivate it is because it’s very rare, even in the wild.”

Up close, botanists say, the scent is reminiscent of dead rats decomposing next to rotting fish – a smell so surprising from such an innocent-looking plant that it is impossible to resist going back for a second and third whiff. “The smell will intensify over time,” Petitt warned. “In the wild, it’s pollinated by flies. That’s why it’s got that fetid carrion scent.”

The orchid’s natural habitat in western Papua New Guinea, where it grows at altitudes of around 500 metres, is under threat. “A lot of it is due to population expansion, people trying to claim land for redevelopment and housing, as well as forestry and crops. But it’s also because of climate change,” said Petitt.

Visitors who wish to smell the flower will not have much time. The garden closes for a week for Christmas on Tuesday, and by the time it reopens, Petitt thinks its putrid odour will have disappeared. But she hopes that those who do catch a whiff will also get a sense of the need for plant conservation and the work botanic gardens do to preserve plant diversity – even when that involves nurturing a flower which, to her, smells like “very sweaty socks and shoes”.

“We don’t have any prejudices in the plant world,” she said. “All plants are valued as being part of our rich and broad diversity.”

She worries about what the future holds for plants in the wild. “In botanic gardens, people are doing great research and finding so much out about plants all the time. That’s uplifting. But when you think about the bigger global community, it can be quite depressing. A lot of the world’s population don’t have that same appreciation of the value of plants that we do in the botanic garden.”

Petitt finds it hard to imagine this will change. “It’s not even ignorance. Some people are oblivious to [the fact] that, without plants, nothing else could exist,” she said.

During the July heatwave this year, temperatures in the garden reached the highest ever recorded by the Met Office in the history of the UK – 38.7C. For Petitt and other staff, it was a grim day.

“Having the hottest day on record here has highlighted issues about climate change. It made it seem more real to people, particularly I think to members of the public… You really think: something dramatic and radical is happening to the climate for it to have got this hot here.”

It focused her thoughts on the potential impact of the climate crisis on a garden that was first planted by Charles Darwin’s tutor, John Stevens Henslow, in the 1830s. “We have since started looking much longer-term at how we approach climate and irrigation and management of plants.”

Already, she said, flowering times are changing and there are plants that are coming through on the garden’s Mediterranean beds that they would not have tried growing in the past.

She finds it difficult to predict what the future holds for the garden, which has been open to the public for 173 years and is home to some of the rarest plants in the world, including some that are now extinct in the wild. “Nobody can really say, absolutely, what impacts climate change will have.”

But she is optimistic that whatever happens, the garden will always offer a sanctuary – however smelly – for plants and humans alike, and that this will have its own modest impact on the planet.

That is why a plant that stinks of rotting flesh felt like the best early Christmas present. “I hope our visitors will go away with a greater understanding and appreciation of the natural world,” she said.