To the rainforests of the Amazon and the mountains of Borneo, teams of explorers went forth from Kew Gardens to scour the world for undiscovered plants. One researcher stayed at home, went for lunch, and stumbled across a new species in Kew's own glasshouse.

Iain Darbyshire, a curator of African Botany, was strolling through the Princess of Wales conservatory during his lunch break when he spotted what turned out to be a previously unknown variety of Acanthus.

"I happened to be walking a different way through the glasshouse and noticed it because it was in full flower," said Dr Darbyshire, who has been studying East African Acanthaceae in Kew's Herbarium. "It was just because I was working in the group that I realized it was a new species."

The plant, now known to be part of the genus Isoglossa, was being used as tropical bedding because of its attractive leaves. It had been sent to Kew from Tanzania in the 1990s but misclassified under a different genus, Justicia.

"It was a great day — a real surprise. It’s very unusual and quite satisfying," Dr Derbyshire said. The plant, similar to a common garden shrub known as Bear's Breeches, looks a bit like mint, he said — "it would make quite a nice tropical border plant."

Dr Darbyshire later discovered the species, thought to be endangered, had first been collected 100 years ago, and a specimen from 1950 was sitting in the Herbarium collection. On it was noted: "name urgently required." 

A small matter of 60 years later, it's now known as Isoglossa variegata.

Read more at the Times of London.