Smallest waterlily in the world brought back from the brink of extinction at Kew Gardens

The Royal Botanic Gardens, Kew’s top propagation ‘code-breaker’, horticulturist Carlos Magdalena, has cracked the enigma of growing a rare species of African waterlily — believed to be the smallest waterlily in the world with pads than can be as little as 1cm in diameter — bringing it back from the brink of extinction; a fitting success story to celebrate International Day for Biological Diversity on 22 May 2010.

This ‘thermal’ waterlily (Nymphaea thermarum), so named because it grows in freshwater hot springs, was discovered in 1985 by German botanist Professor Eberhard Fischer of Koblenz-Landau University. It was endemic to just one known location in Mashyuza, Rwanda, in the south west of the country. However, it disappeared from this location about two years ago due to over-exploitation of the hot spring that fed its fragile habitat. Water was prevented from reaching the earth’s surface resulting in the desiccation of the few square metres where this species grew and no plant is known to have survived in the wild.

Luckily, Professor Eberhard Fischer realised that the species was in jeopardy and he transported a few specimens to Bonn Botanic Gardens soon after its discovery. At Bonn, horticulturists were successful at preserving these valuable specimens and indeed they lasted for more than a decade. However, the species proved extremely difficult to propagate.

As a result of a conservation plant exchange between Bonn and Kew, a handful of seeds and pre-germinated seedlings reached Kew in July 2009. All other known waterlily species start life as submerged plants until large enough to send pads to the surface. Therefore Nymphaea thermarum seedlings were initially grown submerged like any other waterlily. But, at both botanic gardens, this method was unsatisfactory: seedlings were barely clinging on to life and did not develop to adult stages.

Carlos, who has a track record of bringing the rarest and most difficult plants back from the brink, took on the challenge of learning the secrets of successfully propagating Nymphaea thermarum over many months.

He ran a series of trials involving a range of temperatures, water hardness, pH and depth. Plants grown in harder water at shallower depths seemed to develop further. However, no plant reached maturity, which was disappointing; as it seemed that every possible permutation known to have an influence on aquatic plant growth had been tested. Everything except the concentration of CO2 and other gases, such as O2, which are found in much smaller concentrations in water than in the air. Or, perhaps there was something crucial in the natural habitat of which he was not aware?

So the next step was clear: Carlos needed to start investigating ways to increase the carbon dioxide concentration in the water available to the plants whilst gathering information on the natural habitat.

Returning to the original German description of the species and its natural habitat supplied the final clue: “it grows in damp mud caused by the overflow of a hot spring. Water reaches the surface at 50C but the plant colonizes an area where the water has cooled to a temperature of 25C”. This meant that, unlike all other known waterlily species, Nymphaea thermarum did not grow submerged in the deep waters of lakes, rivers or marshes. The revelation was that this small, extremely rare and unusual species, with a spread of only 5 to 20cm, grows in the damp conditions at the edge of a thermal hot spring — and this was the vital clue needed to crack the code.

With this knowledge Carlos did one final trial. He placed seeds and seedlings into pots of loam within small containers filled with water, thus keeping the water at the same level as the surface of the compost, at a temperature of 25°C. In this way, the last remaining individuals of the species could be exposed to the higher concentrations of carbon dioxide and oxygen in the air. And to his surprise and joy, soon the plants started to improve and after a few weeks, eight plants began to flourish, growing to maturity with thicker, greener and wider leaves. In November 2009, Kew’s collection of Nymphea thermarum flowered for the first time.

Carlos Magdalena says,”When I received this donation from Bonn, I realised how important it was for the survival of the species to find a way of growing them successfully. At first they didn’t seem to respond to any of the traditional ways of treating these plants and they remained weak and failed to develop and eventually died. It was only when I searched a little deeper that the key I needed came to the surface. Now we have over 30 healthy baby plants growing here at Kew and some are producing seeds so soon we may have an army of these tiny waterlilies here at Kew. Its future in botanical collections seems secured for the long term.”

He adds, “Waterlilies are among the most ancient of flowering plants. This species could provide information about the evolution of flowering plants as it is truly unique. Our immediate priority is the ex situ conservation of the species and thereafter, if the natural flow of water in its historic location can be restored, plants grown at Kew can then be reintroduced into the wild. Also, this species may provide an opportunity to breed beautiful small and compact waterlily hybrids that don’t need a pond. Gardeners would love something like this, the advent of the ‘no-waterlily’.”

Professor Stephen Hopper, Director of the Royal Botanic Gardens, Kew says, “Kew is one of those places that offers a sense of hope in a time of relative doom and gloom about the state of the natural world, where individuals, by doing practical things with plants, can make a real difference to biodiversity conservation. Kew’s Breathing Planet Programme is about harnessing Kew’s horticultural and plant science expertise to support conservation around the world.”

He adds, “Waterlilies have long been associated with Kew — we have an entire glasshouse dedicated to them that is very popular with our visitors in the summer — and Kew was the first botanic garden to grow the giant waterlily, Victoria amazonica. Therefore, for Kew to pay a vital role in saving this tiny species of waterlily is truly thrilling. We hope in the near future it will be restored to its natural habitat and we will try to collect seeds for safekeeping in Kew’s Millennium Seed Bank and repatriation to Rwanda.

“The Nymphaea story also illustrates a broader biodiversity issue — the plight of ephemeral wetlands or temporary pools, on soil or rock, worldwide. Typically, these places are small in areal extent and often targeted for uses that threaten biodiversity. Yet seasonal wetlands often are richer in endemic species of plants and animals than ‘traditional’ wetlands of permanent water. Particularly in the face of global warming, it is vital for biodiversity conservation, and for human well-being in many places, that such seasonally wet havens are afforded every protection, and their biodiversity is nurtured back from the brink of extinction.”

Professor Eberhard Fischer, who discovered Nymphaea thermarum, says, “When I visited Kew earlier this year I couldn’t believe that Nymphaea thermarum, which we thought had gone extinct about two years ago, was thriving. These 30 plants were the last viable population of this species on the planet and thanks to the work done at Kew we have an opportunity to secure the future of this fascinating, little waterlily.”

On Saturday 22 May 2010 visitors to Kew Gardens will be able to see Nymphaea thermarum on display in the Secluded Glasshouse, along with other rare and endangered plants from Kew’s conservation nursery. Free guided tours — Biodiversity – what’s it all about? — will take place from 10am. Tours start at the Guides’ Desk, Victoria Plaza. See www.kew.org/events for tour times.

Visitors to Wakehurst Place in Sussex on Saturday 22 May will also be able to see a display of rare and endangered plants brought back from the brink of extinction thanks to the scientists from Kew’s Millennium Seed Bank and horticulturists from Wakehurst Place. These include Musa itinerans, the wild pink banana from China, that was the species chosen to represent the Millennium Seed Bank partnership reaching its target of banking 10% of the world’s wild plant species; the starved wood sedge (Carex depauperata), a rare UK native which is being reintroduced to SE England and Banksia brownii, a rare Australian species, saved in the Millennium Seed Bank, and also reintroduced to the wild.

Thanks to Carlos Magdalena’s breakthrough in propagating Nymphaea thermarum, Bonn Botanic Gardens have reported that they have now successfully started to propagate this plant too.

For further information please call the Royal Botanic Gardens, Kew press office. Bronwyn Friedlander, Bryony Phillips, Jo Maxwell and Tarryn Barrowman on + 44 (0)20 8332 5607 or email [email protected]

A Kew film, ‘Plants back from the brink’, is available for use online. Please see www.kew.org/back-from-the-brink

Photos of Nymphaea thermarum are available to download here http://www.kew.org/press/images/Nymphaea_tiny%20waterlily.html

Photos of other rare plants from Kew’s conservation nursery are available to download here http://www.kew.org/press/images/Kew_conservation_plants.html

Please contact the Kew press office for a user name and password.

Notes to Editors:

Carlos Magadalena is part of a team of horticulturists based in Kew’s Tropical Nursery. It is here that many rare and endangered plants are brought back from the brink of extinction. One such success story is Café Marron (Ramosmania rodriguesii), critically endangered and endemic to the Indian Ocean island of Rodrigues.

Thought extinct for 40 years, one tree was rediscovered by a local school boy and cuttings were sent to Kew Gardens in 1986. In 2001, Kew Gardens sent eleven rooted cuttings back to the island to be reintroduced. Although several generations of Café Marron cuttings continued to thrive in Kew’s glasshouses and regularly flowered, they had never set seed until Carlos made a breakthrough in successfully pollinating the flowers. In 2003 the Café Marron bore its first fruit with viable seeds. This made possible the reintroduction of this species in the wild as cross-pollination of the seedlings regularly produced seed. The plants were also now capable of propagating themselves and sustaining a wild population. Carlos has repatriated seedlings to Rodrigues, most recently in April 2010 when he travelled to the island with more than 500 seeds and planted new saplings on the island. http://www.kew.org/plants-fungi/Ramosmania-rodriguesii.htm

Professor Stephen Hopper is the 14th Director of the Royal Botanic Gardens, Kew.

He is a plant conservation biologist, best known for pioneering research leading to positive conservation outcomes in south-west Australia (one of the few temperate-zone global biodiversity hotspots) and for the collaborative description of 300 new plant taxa (eucalypts, orchids, Haemodoraceae). He is also the author of more than 200 scientific publications, including several books and scientific monographs. Apart from extensive research in southwest Australia, Steve Hopper has explored Australian deserts since 1980, and conducted field research in South Africa and the USA.

While Foundation Professor of Plant Conservation Biology at The University of Western Australia from 2004-2006, he developed new theory on the evolution and conservation of biodiversity on the world’s oldest landscapes, and led the establishment of new degrees in conservation biology. He joined Kew in October 2006. Previously he was Director of Kings Park and Botanic Garden (from 1992), and from 1999 to 2004 served as Chief Executive Officer of the Botanic Gardens and Parks Authority (which manages Kings Park and Botanic Garden and Bold Park), leading the delivery of improvements to programmes and infrastructure to world-class standards. More information here http://www.kew.org/about-kew/steve_hopper.html

The Royal Botanic Garden, Kew

The Royal Botanic Gardens, Kew is a world famous scientific organisation, internationally respected for its outstanding living collection of plants and world-class Herbarium as well as its scientific expertise in plant diversity, conservation and sustainable development in the UK and around the world. Kew Gardens is a major international visitor attraction. Its landscaped 132 hectares and RBG Kew’s country estate, Wakehurst Place, attract nearly 2 million visitors every year. Kew was made a UNESCO World Heritage Site in July 2003 and celebrated its 250th anniversary in 2009. Wakehurst Place is home to Kew’s Millennium Seed Bank, the largest wild plant seed bank in the world. RBG Kew and its partners have collected and conserved seed from 10% of the world’s wild flowering plant species (c.30, 000 species) and aim to conserve 25% by 2020.

Kew’s Millennium Seed Bank partnership has already achieved so much, and its enormous potential for future conservation can only be fulfilled with the support of the public and other funders. Kew needs to raise significant funds both in the UK and overseas. Members of the public can support the work of Kew’s Millennium Seed Bank partnership by getting involved with the ‘Adopt a Seed, Save a Species’ campaign. For £25 an individual can adopt a seed or for £1000 anyone can save an entire species. http://www.kew.org/adoptaseed

‘Biodiversity Year at Kew’ in 2010 will celebrate the importance of plant diversity in underpinning biodiversity through a programme of themed and seasonal horticultural displays, art exhibitions, educational activities for all the family and scientific announcements. For a full programme of events see www.kew.org/press/2010.html or visit www.kew.org/biodiversity

The Royal Botanic Gardens, Kew is part of the world-wide celebrations of 2010 as the International Year of Biodiversity, and is one of over 300 UK organisations, charities and groups supporting this global awareness campaign. The diversity of life on earth is crucial for human well-being and now is the time to act to preserve it. For information on events, initiatives and exhibitions across the UK during 2010 visit www.biodiversityislife.net

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