How is the Genus Coping?

Rhododendron is a complex genus of some 1,300 taxa (species, subspecies, varieties), of northern hemisphere origin. Taxa are found from lowland subtropical forest to alpine tundra, and have growth habits ranging from forest trees to epiphytes and creeping swamp plants. Conservation assessments, using international conservation criteria, have resulted in 726 taxa being Red Listed (1&2), that is, those species are deemed to be at risk or threatened with extinction in their native habitat. Cultivation in ex-situ collections is one way to conserve Red List taxa; 903 taxa are in cultivation internationally, with some 538 taxa present in New Zealand collections including Red List taxa (3) and several hundred individual accessions of wild-source origin.

1. MacKay MB, Smith GF, Gardiner SE. 2017. New Zealand collections of Rhododendron as a resource for ex situ conservation. New Zealand Journal of Botany 55(2): 193-214.

2. Established in 1964, The International Union for Conservation of Nature’s Red List of Threatened Species is the world’s most comprehensive information source on the global conservation status of animal, fungi and plant species. It assesses species into nine categories: Not Evaluated, Data Deficient (DD), Least Concern (LC), Near Threatened (NT), Vulnerable (VU), Endangered (EN), Critically Endangered (CR), Extinct in the Wild (EW) and Extinct (EX).

3. MacKay M, Hootman S, Smith G, Thomson D, Gardiner S, Smith P. 2018. Updated global analysis for ex situ conservation of Rhododendron L. (Ericaceae). Report to Botanic Gardens Conservation International (London); Massey University.

Future preservation

What Are We Doing About It?

Formed in 2018, the New Zealand Rhododendron ex-situ Conservation Project (the Project), is a collaboration among scientists, rhododendron collection holders, botanists and conservation authorities in New Zealand and internationally. The project goal is to analyse Rhododendron collections in New Zealand in relation to those held globally, and to develop management strategies, nationally and for individual collections, that contribute to the conservation of Rhododendron species. Ex-situ conservation (where species at risk of extinction in their native habitat are conserved by growing them in living collections in botanic gardens or similar sites) is positioned within the framework of the Global Strategy for Plant Conservation and its 16 Targets⁴. Of particular focus in New Zealand are Target 2 (Red List assessment) which prioritises any ex-situ action, and Target 8 (achieve 75% of Red List taxa growing in cultivation), which directs that ex-situ action. Key factors for success in ex situ conservation are the presence of a range of genetically diverse plants of wild-source origin; correct identification and labelling of each individual plant; detailed and accurate record keeping; and skilled cultivation to ensure successful growth and excellent plant health. The broad aims of the New Zealand Project are to: (i) analyse the range of taxa held in New Zealand collections, including taxa that have been present historically, (ii) propagate and disperse those taxa that are held on limited sites, (iii) work with collection holders to analyse individual collections and develop management strategies that facilitate the conservation of threatened taxa held at those sites, e.g. increasing the diversity of each taxon held, (iv) use laboratory analysis, when appropriate, to assess identity and genetic diversity of collections, and (iv) work with international associates to assist with conservation of Rhododendron taxa globally.

⁴ Botanic Gardens Conservation International, 2012. The Global Strategy for Plant Conservation: 2011-2020. Published by Botanic Gardens Conservation International for the Convention on Biological Diversity.

Key Activities

Project Goals

Key goals for participating sites in this project include:

Collaborating with the project team to analyse the collection at that site and determine its significance for conservation, including the identification of taxa that should be propagated

Ensuring accurate plant identification and labelling, with an associated set of detailed records so that individual plants can be located, propagated as necessary, and tracked when sent to other collections

Working with the project team to determine a programme of collection development, propagation, and collection administration appropriate to that collection

Collaborating with the project team, and other New Zealand collections, to develop a network of suitable sites in New Zealand that together can successfully conserve the range of Rhododendron taxa held in New Zealand

In New Zealand, the Pukeiti Rhododendron Trust is partnered with Massey University Te Kunenga ki Pūrehuroa, the Taranaki Regional Council, the New Zealand Rhododendron Association, and the Pukeiti Garden Forum.

International connections include the Kunming Botanical Institute in the People’s Republic of China, the Rhododendron Species Foundation in the USA, the Global Rhododendron Conservation Consortium, Botanic Gardens Conservation International and the Royal Botanic Garden Edinburgh.

There are also now several partner gardens throughout New Zealand, growing the rare and endangered rhododendrons from the Project that are best suited to their growing conditions.

Gardens that are open to the public include Gore’s Bannerman Park in the South Island and Heritage Park in the Manawatu, Eden Garden in Auckland, and Wharepuke and Whangarei Quarry Gardens in Northland.

The following are places with significant collections that include Tannock Glen, Dunedin Botanic Garden and Cross Hills Garden in the Manawatu.

Plants are also held in a few private gardens, including Omahuri Garden in Palmerston North, Woodchester Garden in North Canterbury and a private collection in Dunedin.

Plants are also being made available to PRT members through the annual Member’s Plant List Scheme, which has been running since the late 1970s.

Project Partners and Connections

Who Is Involved?

2023 Project Update

Members are updated on the Project’s achievements and progress through briefings at member events and annually via The New Zealand Rhododendron journal, a joint publication between the PRT and the NZRA, issued each December.

Click here to read the 2023 Update.

Become a member

Sign up here

No matter the season, there is always something to see at Pukeiti so come enjoy the beauty of the gardens.