Mignonette leek orchid rediscovered after almost a century presumed extinct

The mignonette leek orchid, which was last documented in 1933, has been rediscovered in Australia during surveys conducted after the Black Summer wildfires in 2019-20

By Alice Klein

A delicate lemon-scented orchid species that was thought to have disappeared in the 1930s has been rediscovered in south-east Australia.

“It’s not often that you’re able to come across something you thought was extinct, so it’s really lovely,” says Noushka Reiter at Royal Botanic Gardens Victoria in Melbourne.

Prasophyllum morganii – commonly known as the mignonette leek orchid – was first documented in 1929 when a cattle grazier called Harry Morgan noticed several on his property near Cobungra, Victoria, and sent some to an amateur botanist called William Henry Nicholls.

Nicholls made drawings of the orchids – which he named after Morgan – and preserved some as dried flowers and some in alcohol. Eight of these specimens – including those from 1929 and others collected from the same site in 1933 – were lodged at herbariums in Melbourne and Adelaide.

Orchid experts have since tried to track down the species again, but without further sightings, it was presumed extinct.

Then, in 2020, after Australia’s east coast was ravaged by the Black Summer wildfires, the Australian government funded detailed surveys of the burnt areas to find out which plants and animals were left.

During these surveys, four populations of orchids that looked like they might be P. morganii were discovered at Nunniong Plain and Timbarra North Plain in Victoria and Sawyers Hill and Kellys Plains in New South Wales.

Reiter and her colleagues compared these orchids with the old P. morganii herbarium specimens to see if they were the same. They rehydrated the 90-year-old dried flowers to properly visualise their size and shape and found that they matched the newly found specimens.

“It’s an adorable species,” says Reiter. “It comes in a variety of colours from purple to light green and has cute, squashed little flower heads and a lemon scent,” she says.

As it turns out, a population of P. morganii had already been located by a botanist in 2000 in Kosciuszko National Park in New South Wales, but until the latest study, it was thought to be a separate species.

This is because Nicholls threw everyone off by getting “a bit carried away” with his original drawings of P. morganii, says Reiter. “He drew it with 80 flowers but when we pulled out his old specimens we saw it actually had 30 less flowers,” she says.

Only a few hundred individual P. morganii plants were counted during the 2020 surveys, suggesting they are still vulnerable to extinction. Reiter and her colleagues are now cultivating the species at Royal Botanic Gardens Victoria and hope to grow enough plants to be able to return some to their native habitats.

Journal reference: Phytotaxa, DOI: 10.11646/phytotaxa.528.2.1

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