12 February 2020

Meet the plant undateables

These are some of the loneliest plants in the world. But is there hope for them yet?

By Katie Avis-Riordan

Encephalartos woodii

It’s not just humans that have trouble finding their perfect match. Some plants have it even harder.

From the only palm left in its species to a solitary British orchid, here are some of the loneliest plants in nature.

Wood’s cycad (Encephalartos woodii)

When it comes to plant undateables then Encephalartos woodii surely tops the list.

It’s so lonesome and rare that only one specimen has ever been found in the wild.

This single male cycad was discovered in 1895 by botanist John Medley Wood on the edge of the Ngoye Forest in South Africa.

A female Encephalartos woodii has never been found. The problem is that cycads are dioecious, meaning the male and female reproductive organs are in separate individual plants.

So, without a female, pollination and natural reproduction aren’t possible.

But there’s still some hope. A female plant may be out there undiscovered somewhere in the wild. There’s also the possibility the male plant will experience a spontaneous sex change, which has happened with other cycads.

A cutting from the original male plant arrived at Kew in 1899. Though Extinct in the Wild, other males can also be found growing in botanic gardens and private collections around the world.

You can find our handsome male singleton living in the Temperate House.

Encephalartos Woodii
Encephalartos woodii is the loneliest plant at Kew © RBG Kew / Jeff Eden

The lonely palm (Hyophorbe amaricaulis)

Commonly known as the loneliest of all palms is the Hyophorbe amaricaulis, endemic to Mauritius.

The species was thought to be extinct until one lone individual was discovered in a botanic garden in Mauritius in 1942.

Extinct in the Wild, the palm produces female and male flowers at different times during the flowering season.

This means no natural pollination occurs and the plant's flowers have to be hand pollinated to produce seeds, which are not able to be germinated under normal horticultural conditions.

One of our scientists, Dr Viswambharan Sarasan, set out to study whether this threatened palm could be propagated from seeds.

Collecting seeds from the plant in Mauritius, he attempted 'embryo rescue' to grow them in our laboratory. These embryos germinated and produced seedlings but despite these promising results they failed to survive beyond weaning stage.

To save this species from extinction, collaborative research is desperately needed to identify the right conditions for successful weaning of plants for potential reintroduction back into the wild.

The lonely palm (Hyophorbe amaricaulis)
The lonely palm (Hyophorbe amaricaulis) © Christian Hauzar/Wikimedia Commons

Lady’s slipper orchid (Cypripedium calceolus)

Another companionless plant is the British lady’s slipper orchid.

There’s only one specimen of its species left in the wild in Britain.

Though abundant in other countries, here in the UK, the orchid is so rare that its location is top secret and even has its own warden for protection.

So what’s the reason for this lonely life?

Orchids are fussy, and need very specific habitats to germinate. The beautiful species, with its showy yellow and maroon flowers, also became the victim of overcollection by orchid enthusiasts.

By the early 1900s, Cypripedium calceolus was believed to be extinct in Britain, until this one singular plant was rediscovered.

That’s when the Cypripedium Committee was set up to guard the threatened plant and develop a conservation strategy.

The flowers were hand pollinated, and the resulting seeds were sent to Kew, where, following experimentation in our micropropagation laboratory, we managed to successfully propagate the plant.

The method of germination we developed is now routinely in use, so the future of this orchid is looking a lot less lonely.

Lady's slipper orchid
Lady's slipper orchid (Cypripedium calceolus) © RBG Kew

Café marron (Ramosmania rodriguesii)

For a long time, only one solitary plant of Ramosmania rodriguesii was known to exist in the wild.

Endemic to the island of Rodrigues in the Indian Ocean, café marron didn’t seem to be capable of producing seeds.

Its flowers are self-incompatible, which means the pollen from the flowers of an individual plant cannot fertilise the ovules of its own flowers.

This is to prevent inbreeding and promote outcrossing, increasing the genetic strength of offspring.

This is a major drawback when there is only one specimen left in the plant’s entire world population.

Using cuttings from the original wild plant, clones of the species were successfully propagated at Kew, but still, the flowers could not be fertilised to produce seeds.

Café marron (Ramosmania rodriguesii)
Café marron (Ramosmania rodriguesii) © RBG Kew

That’s where Kew's Scientific and Botanical Research Horticulturist Carlos Magdalena comes in.

In a major breakthrough, Carlos, nicknamed the 'Plant Messiah', discovered a technique to bypass the plant's self-incompatibility mechanism.

He ‘tricked’ the plant by giving it a heat shock resulting in the production of a small number of viable seeds.

Since then, several seeds have been successfully germinated and grown at Kew, and repatriated and grown at a nursery on Rodrigues.

The aim is to eventually re-establish a wild population on the island.

Look out for café marron growing in our Palm House and Princess of Wales Conservatory.

Brought back from the edge of extinction, this shows there’s still hope for those unlucky plants struggling in the dating game.

Advances in science and horticulture could be just the helping hand that these lonely plants need.

Grevillea ‘Coastal Sunset’

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