Conserving threatened Rhododendron species

At the Bergen University Gardens in Western Norway, we are putting extra effort into long term conservation of threatened species.


26 May 2023




Prioritizing survival of threatened species

Mortality is not unusual in botanic gardens. It is an inevitable consequence of attempting to grow a great many different plants, often of wild origin and from across the world. Each species or even individual is unique in its ability to thrive given different soils, temperatures, rainfall, and seasonal variability. No garden is immune to sudden calamity, whether that is late frost, drought, infestation, or even fires that might impact entire collections.

With the accelerating loss of biodiversity worldwide we must recognise that some of our collections are too important to leave to chance.

The price of failure for the custodian of the last living specimen is the loss of up to millions of years of unique accumulated evolutionary history with all its future potential uses and intrinsic value for everyone. For any single botanic garden, this would be an intolerably heavy responsibility.

Botanic gardens work together

However, we are not alone. Thousands of botanic gardens worldwide have the potential to spread both the burden and the risk of looking after these treasures, when we work together and coordinate our efforts. Not every garden can look after everything – the numbers of species are just too high – but we are well placed to focus on our own areas of expertise.

Here at the Bergen University Gardens, we have the ideal conditions, established knowledge, and collections of Rhododendron (Jørgensen, 1996; Salvesen & al., 2021) to contribute internationally to conservation of species. Crucially, we are part of an international group of gardens coordinated at the Royal Botanic Garden Edinburgh (RBGE) under BGCI’s ‘Global Conservation Consortium for Rhododendron.

Growing threatened Rhododendron species at the University Garden’s Arboretum

We currently act as a safe site for seven Critically Endangered (CR) and 14 Endangered (EN) Rhododendron species. The IUCN categories of threat reflect the distribution range and rarity of species and the prospects for continuity of their habitats. These factors change over time – often for the worse – and we can expect a proportion of the species in our collections to move to more severe categories.

We are therefore acting to secure all our wild-origin accessions of threatened species, including CR, EN, and dozens more that have been assessed as Vulnerable (VU) or Near Threatened (NT), for example through vegetative propagation and protected overwintering.

By sharing information and material, we can aim to both back up our unique collections and better represent the genetic diversity of species in a ‘meta-collection’ spread across multiple gardens.


Threatened species at the Bergen University Gardens – more than just Rhododendron

Rhododendrons are not the only threatened species we protect at the University Gardens. We hold collections of threatened conifers, such as Wollemia nobilis, and of threatened species of Fraxinus and Sorbus. We coordinate a dedicated GCC for the other Ericaceae mega-genus, Erica (Pirie & al., 2022), and also work nationally with seed banking of rare and endangered species in Norway.

Through our collections and exhibits we hope that our visiting public will be inspired to support work with BGCI and our international partners to promote conservation of biological diversity.


Bergen Botanic Garden Interpretation Panel for Rhododendron kotschyi
UiB Interpretation panel for threatened Rhododendron kotschyi.

Contributed by:

Michael Pirie, Associate Professor and curator of the Arboretum at the University Gardens, University Museum of Bergen, Norway.

Adapted from a longer article in Norwegian currently in press at ‘Lapprosen’, the journal of the Norwegian Rhododendron society (‘Den norsk Rhododendronforening’).



Gibbs, D., Chamberlain, D., & Argent, G. 2011. The Red List of rhododendrons. Botanic Gardens Conservation International, UK.

Jørgensen, P.M. 1996. Rhododendron i Det norske arboret på Milde. Fagbokforlaget Vigmostad & Bjørke AS.

Pirie, M.D., Blackhall-Miles, R., Bourke, G., Crowley, D., Ebrahim, I., Forest, F., Knaack, M., Koopman, R., Lansdowne, A., Nürk, N.M., Osborne, J., Pearce, T.R., Rohrauer, D., Smit, M., & Wilman, V. 2022. Preventing species extinctions: A global conservation consortium for Erica. PLANTS, PEOPLE, PLANET 4: 335–344.

Salvesen, P.H., Moe, B., Nilsen, L.H., & Spildo, S. 2021. Levende museum og botanisk skattkammer. Bergen: Stiftelsen det Norske Arboret & Bodoni forlag.

Pink flowered Rhododendron platypodum
Rhododendron platypodum. Image:MIchael David Pirie