Creating a metacollection: the New Zealand National Rhododendron Collection and ex situ Conservation Project
DOI:
https://doi.org/10.24823/Sibbaldia.2026.3628Keywords:
Rhododendron, Ex situ conservation, New ZealandAbstract
Various analyses have indicated that gardens in New Zealand hold a collection of Rhododendron species that can make a contribution to international ex situ conservation. In consequence, a project was initiated in 2017 to manage the New Zealand holdings, which are held on a range of sites, as a metacollection for conservation. This article describes the development of that project and its operation up to 2026. It provides a summary of the context and priorities for Rhododendron conservation, and outlines the project’s objectives and development. Project activities are described under six categories: (1) the search for, and propagation and distribution of plants; (2) the network of collections and the National Collection; (3) communication and external relations; (4) data and analysis; (5) biosecurity, including the framework that controls importation of seed into New Zealand; (6) research. The project is based on a series of global analyses carried out in the period 2016–2018. Since then, however, the global situation has changed. A new global analysis is therefore required to reflect recent changes in threat status and collection holdings.
References
ANON (2015). In the footsteps of Kingdon-Ward: plant collecting North of Burma triangle with Jeremy Thomson and Shashil Dayal. The New Zealand Rhododendron, 3: 2–23. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
ARGENT, G. (2015). Rhododendron of the Subgenus Vireya. 2nd edn. RBGE, Edinburgh.
ARGENT, G. & MAMBRASAR, Y.M. (2019). Rhododendron widjajae (Ericaceae, section Schistanthe) a new species from Sulawesi. Reinwardtia, 18(1): 27–30.
BAILEY, G. (2024). Kunming 2024. The New Zealand Rhododendron, 12: 62–63. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
BOTANIC GARDENS CONSERVATION INTERNATIONAL (2012). Global survey of ex situ Rhododendron collections. Botanic Gardens Conservation International, Richmond, UK. Available online: www.bgci.org/wp/wp-content/uploads/2019/04/Global_Survey_of_Ex_situ_Rhododendron_Collections.pdf (accessed January 2026).
BOTANIC GARDENS CONSERVATION INTERNATIONAL (2016). North American Botanic Garden Strategy for Plant Conservation, 2016–2020. Available online: www.bgci.org/resources/bgci-tools-and-resources/north-american-botanic-garden-strategy-for-plant-conservation (accessed January 2026).
BOTANIC GARDENS CONSERVATION INTERNATIONAL (2017). BGCI Plant Search. Available online: https://plantsearch.bgci.org (accessed January 2017).
BIOTANZ (UNDATED). BiotaNZ database. Available online: https://biotanz.landcareresearch.co.nz (accessed January 2026).
BLACKMORE, S. (2024). Botanic gardens are vital for delivering the Kunming–Montreal global biodiversity framework. Biological Diversity, 1(3–4): 120–123. https://doi.org/10.1002/bod2.12022
BLACKMORE, S., GIBBY, M. & RAE, D. (2011). Strengthening the scientific contribution of botanic gardens to the second phase of the Global Strategy for Plant Conservation. Botanical Journal of the Linnaean Society, 166: 267–281. https://doi.org /10.1111/j.1095-8339.2011.01156.x
BROOKER, A. (2023a). Visit to Seattle and the Rhododendron Species Symposium 2023. The New Zealand Rhododendron, 11: 49–51. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
BROOKER, A. (2023b). The collections network of the New Zealand ex situ Rhododendron Conservation Project. Oral presentation to the Australian Rhododendron Society Annual Conference, Burnie, Tasmania, 14 October 2023.
BROOKER, A. (2024). Andrew’s time abroad: re-establishing contacts overseas. The New Zealand Rhododendron, 12: 50–53. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
BROOKER, A. (2025). Heading to Nova Scotia: the American Rhododendron Society annual convention. The New Zealand Rhododendron, 13: 48–50.
BUBLITZ, L. (2020). Cross Hills: the Wilson family’s legacy. The New Zealand Rhododendron, 8: 6–13. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
BUBLITZ, L. (2021). Eden Gardens expanding the ex situ Rhododendron Conservation Project. The New Zealand Rhododendron, 9: 42–45. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
CARVER, J., COOPER, J., VIGNAUX, M. & WILTON, A. (2007). What’s in a name? New Zealand Organisms Register scope. Report prepared for the New Zealand TFBIS programme.
CASTENADA-ÁLVAREZ, N.P., DE HAAN, S., JUAREZ, H., KHOURY, C.K., ACHICANOY, A., SOSA, C.C., BERNEAU, V., SALAS, A., HEIDER, B., SIMON, R., MAXTED, N. & SPOONER, D.M. (2015). Ex situ conservation priorities for the wild relatives of potato (Solanum L., section Petota). PLoS ONE, 10(4): e0122599. https://doi:10.1371/journal.pone.0122599
CAVENDER, N., WESTWOOD, M., BECHTOLDT, C., DONNELLY, G., OLDFIELD, S., GARDNER, M., RAE, D. & MCNAMARA, W. (2015). Strengthening the conservation value of ex situ tree collections. Oryx, 49(3): 416–424. https://doi.org/10.1017/S0030605314000866
CIRES, E., DE SMET, Y., CUESTA, C., GOETGHEBEUR, P., SHARROCK, S., GIBBS, D., OLDFIELD, S., KRAMER, A. & SAMAIN, M. (2013). Gap analysis to support ex situ conservation of genetic diversity in Magnolia, a flagship group. Biodiversity Conservation, 22: 567–590. https://doi.org/10.1007/s10531-013-0450-3
CONVENTION ON BIOLOGICAL DIVERSITY (2012). Global Strategy for Plant Conservation 2011–2020. Botanic Gardens Conservation International, Richmond, UK. Available online: www.bgci.org/files/Plants2020/GSPCbrochure/gspc_english.pdf (accessed January 2026).
DAVIES, S. (2016). Omahuri: place of young trees. The New Zealand Rhododendron, 4: 28–32. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
DAWSON, M. (ED.) (2010). Documenting New Zealand’s cultivated flora: a supermarket with no stock inventory. Report from a TFBIS-funded workshop held in Wellington, New Zealand.
DAWSON, M. (2022). Taking stock: resolving New Zealand’s cultivated plants problem. Ministry for Primary Industries (MPI) Project 19008 Completion Report, submitted to MPI 20 January 2022. Project report available from Murray Dawson.
DICKSON, M. (2009). The Plants Biosecurity Index (PBI). New Zealand Garden Journal, 12: 8–9.
ENNOS, R.A., FRENCH, G.C. & HOLLINGSWORTH, P.M. (2005). Conserving taxonomic complexity. Trends in Ecology & Evolution, 20(4): 164–168. https://doi.org/10.1016/j.tree.2005.01.012
FARNSWORTH, E.J., KLIONSKY, S., BRUMBACK, W.E. & HAVENS, K. (2006). A simple set of decision matrices for prioritising collection of rare plant species for ex situ conservation. Biological Conservation, 28: 1–12. https://doi.org/10.1016/j.biocon.2005.09.010
FRODIN, D.G. (2004). History and concepts of big plant genera. Taxon, 53(3): 753–776. https://doi.org/10.2307/4135449
GARDINER, S.E. (2023). Vulnerable AustraIian Rhododendron – one or two species? Oral presentation to the Australian Rhododendron Society Annual Conference, Burnie, Tasmania, 14 October 2023.
GARDINER, S.E., WIEDOW, C., KIRK, C., GRANDE, A. & DENG, C. (2019). Molecular analysis and classification of Australia’s Rhododendron. A Plant & Food Research report prepared for the Australian Rhododendron Society. Milestone No. 74504. Contract No. 33804. PFR SPTS No. 18907.
GIBBS, D., CHAMBERLAIN, D. & ARGENT, G. (2011). The Red List of Rhododendrons. Botanic Gardens Conservation International, Richmond, UK. Available online: https://portals.iucn.org/library/node/10132 (accessed January 2026).
GLOBAL CONSERVATION CONSORTIUM FOR RHODODENDRON (2026). About the Global Conservation Consortia. Available online: www.bgci.org/our-work/networks/global-conservation-consortia-gcc (accessed January 2026).
GLOBAL PARTNERSHIP FOR PLANT CONSERVATION (2025). The Global Strategy for Plant Conservation 2020–2030. Botanic Gardens Conservation International, Richmond, UK. Available online: www.bgci.org/wp/wp-content/uploads/2025/06/GSPCSummaryRed.pdf (accessed June 2026).
GRIFFITH, M.P., CLASE, T., TORIBIO, P., PINEYRO, Y.E., JIMENEZ, F., GRATACOS, X., SANCHEZ, S., MEEROW, A., MEYER, A., KRAMER, A., FANT, J., HAVENS, K. ET AL. (2020). Can a botanic garden metacollection better conserve wild plant diversity? A case study comparing pooled collections with an ideal sampling model. International Journal of Plant Sciences, 181(5): 485–496. https://doi.org/10.1086/707729
HAZARDOUS SUBSTANCES AND NEW ORGANISMS ACT (1996). Available online: www.legislation.govt.nz/act/public/1996/30/en/latest/#DLM381222 (accessed July 2026).
HEYWOOD, V.H. (2017). Plant conservation in the Anthropocene – challenges and future prospects. Plant Diversity, 39: 314–330. https://doi.org/10.1016/j.pld.2017.10.004
HOBAN, S., CALLICRATE, T., CLARK, J., DEANS, S., DOSMANN, M., FANT, J., GAILING, O., HAVENS, K., HIPP, A.L., KADAV, P., KRAMER, A.T., LOBDELL, M. ET AL. (2020). Taxonomic similarity does not predict necessary sample size for ex situ conservation: a comparison among five genera. Proceedings of the Royal Society B, 287: 20200102. https://doi.org/10.1098/rspb.2020.0102
HU, L. (2024). Investigation of taxonomy and diversity of ex situ collections of Rhododendron (subsection Maddenia) for Conservation. Unpublished PhD dissertation, Massey University. Available online: https://research.ebsco.com/c/4egzpd/search/details/oh6dlwllkn?q=ling%20hu (accessed January 2026).
HU, L., GARDINER, S.E., TATE, J.A. & MACKAY, M.B. (2024a). Understanding Rhododendron intraspecific compatibility in botanic garden collections for species conservation. Australian Journal of Botany, 72(6): BT24005. Available online: https://connectsci.au/bt/article/72/6/BT24005/80805/Understanding-Rhododendron-intraspecific (accessed January 2026).
HU, L., MACKAY, M., GARDINER, S.E. & TATE, J.A. (2024b). Rhododendron diversity conservation in global botanic gardens: a case study of Maddenia species. Oryx, 58(5): 576–586. https://doi.org/10.1017/S0030605324000759
HU, L., TATE, J.A., GARDINER, S.E. & MACKAY, M. (2023). Ploidy variation in Rhododendron L. (Ericaceae) subsection Maddenia and its implications for conservation. AoB PLANTS, 15(3): 1–15. Available online: https://academic.oup.com/aobpla/article/15/3/plad016/7116018 (accessed January 2026).
KOZLOWSKI, G., GIBBS, D., HUAN, F., FREY, D. & GRATZFELD, J. (2012). Conservation of threatened relict trees through living ex situ collections: lessons from the global survey of the genus Zelkova (Ulmaceae). Biodiversity Conservation, 21: 671–685. https://doi.org/10.1007/s10531-011-0207-9
LINSKY, J., BYRNE, A., HANDLEY, V., COFFEY, E.E., ALVAREZ-CLARE, S., CROWLEY, D. & MEYER, A. (2024). Integrated plant conservation through the Global Conservation Consortia. Applications in Plant Sciences, 12(3): e11586. https://doi.org/10.1002/aps3.11586
LOWE, R.A.W. (1988). The National Council for the Conservation of Plants and Gardens (NCCPG). Royal New Zealand Institute of Horticulture Annual Journal, 15: 29–31.
LOWE, T. (1989). The way ahead. The Garden, 114: 364–368.
MACKAY, M.B. (1996). Management of the Plant Collection at Eastwoodhill Arboretum. Unpublished PhD dissertation, Massey University. Available online: https://mro.massey.ac.nz/handle/10179/2834 (accessed January 2026).
MACKAY, M.B. (2019). Ex situ conservation and wild-source plant material. The New Zealand Rhododendron, 7: 28–33. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
MACKAY, M.B. (2023). Five years on: a review of the New Zealand Rhododendron ex situ Conservation Project. The New Zealand Rhododendron, 11: 34–41. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
MACKAY, M.B. (2024). Section 26 and ‘not new’: tackling the biosecurity issue. The New Zealand Rhododendron, 12: 54–60. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
MACKAY, M.B. (2025). The New Zealand Rhododendron ex situ Conservation Project: report to the end of October 2025. The New Zealand Rhododendron, 13: 51–57.
MACKAY, M.B. & DAWSON, M.I. (2022). Application APP203943 to the New Zealand Environmental Protection Authority for a Section 26 determination. Available online: www.epa.govt.nz/database-search/hsno-application-register/view/APP203943 (accessed January 2026).
MACKAY, M.B. & GARDINER, S.E. (2017a). A model for determining ex situ conservation priorities in ‘big genera’ is provided by analysis of the subgenera of Rhododendron L. (Ericaceae). Biodiversity Conservation, 26(1): 189–208. Available online: https://link.springer.com/article/10.1007/s10531-016-1237-0 (accessed January 2026).
MACKAY, M.B. & GARDINER, S.E. (2017b). Geographic analysis of Red List Rhododendron (Ericaceae) taxa by country of origin identifies priorities for ex situ conservation. Blumea, 62(2): 103–120. https://doi.org/10.3767/blumea.2017.62.02.05
MACKAY, M.B. & HOOTMAN, S.E. (2019). Examining the significance of the Rhododendron collection at the Rhododendron Species Botanical Garden (Federal Way, WA, USA). Rhododendrons International, 4(1): 1–15. Available online: www.rhododendron.org/ri/v4p1.pdf#zoom=175 (accessed January 2026).
MACKAY, M.B., HOOTMAN, S.E., SMITH, G.F., THOMSON, D., GARDINER, S.E. & SMITH, P. (2018). Updated global analysis for ex situ conservation of Rhododendron L. (Ericaceae). Report to Botanic Gardens International, January 2018. Massey University, Palmerston North, and Botanic Gardens Conservation International, Richmond, UK. Available online: www.arboretumwespelaar.be/userfiles/file/pdf/180000_MacKayETAl_2018_Report_RhododendronGlobalUpdate06.pdf (accessed January 2026).
MACKAY, M.B., SMITH, G. & GARDINER, S.E. (2016). Analysis of geographic and taxonomic groups informs conservation of Rhododendron L. subgenus Vireya (C.B. Clarke) H.F. Copel. (Ericaceae). Blumea, 61(3): 170–180. https://doi.org/10.3767/000651916X693275
MACKAY, M.B., SMITH, G.F. & GARDINER, S.E. (2017). New Zealand collections of Rhododendron as a resource for ex situ conservation. New Zealand Journal of Botany, 55(2): 193–214. http://dx.doi.org/10.1080/0028825X.2017.1291434
MAMBRASAR, Y.M., ELLIOTT, A.C. & CAMERON, K.M. (2024). Two new species of Vireya Rhododendron (Ericaceae), from Tambrauw, Papua, Indonesia. Nordic Journal of Botany, 2024(12): e04545. https://doi.org/10.1111/njb.04545
MAUNDER, M., HIGGENS, S. & CULHAM, A. (2001a). The effectiveness of botanic garden collections in supporting plant conservation: a European case study. Biodiversity Conservation, 10: 383–401. https://doi.org/10.1023/A:1016666526878
MAUNDER, M., LYTE, B., DRANSFIELD, J. & BAKER, W. (2001b). The conservation value of botanic garden palm collections. Biological Conservation, 98(3): 259–271. https://doi.org/10.1016/S0006-3207(00)00160-9
MOONLIGHT, P.W., BALDASZTI, L., CARDOSO, D., ELLIOTT, A., SARKINEN, T. & KNAPP, S. (2024). Twenty years of big plant genera. Proceedings of the Royal Society B: Biological Sciences, 291(2023): 20240702. https://doi.org/10.1098/rspb.2024.0702
MOUNCE, R., SMITH, P. & BROCKINGTON, P. (2017). Ex situ conservation of plant diversity in the world’s botanic gardens. Nature Plants, 3: 795–802. https://doi.org/10.1038/s41477-017-0019-3
MPI (UNDATED). New Zealand Ministry for Primary Industries Plant Biosecurity Index. Available online: https://piersearch.mpi.govt.nz/plants-biosecurity-index (accessed January 2026).
MURDOCH, B. (1994–2001). Dalebrook Nursery collection register. Unpublished collection record donated by B. Murdoch to the New Zealand Rhododendron Project.
OLDFIELD, S. (2010). Plant conservation: facing tough choices. BioScience, 60(10): 778–779. https://doi.org/10.1525/bio.2010.60.10.2
PRITCHARD, D.J., FA, J.E., OLDFIELD, S. & HARROP, S.R. (2011). Bring the captive closer to the wild: redefining the role of ex situ conservation. Oryx, 46(1): 18–23. https://doi.org/10.1017/S0030605310001766
PUKEITI RHODODENDRON TRUST (2023). New Zealand Rhododendron ex situ Conservation Project: Strategy 2019–2024 (revised June 2023). Unpublished document, Pukeiti Rhododendron Trust, received at the board meeting of June 2023.
RAE, D. (2011). Fit for purpose: the importance of quality standards in the cultivation and use of live plant collections for conservation. Biodiversity Conservation, 20: 241–258. https://doi.org/10.1007/s10531-010-9932-8
SHARROCK, S. (2020). Plant Conservation Report 2020: A review of progress in implementation of the Global Strategy for Plant Conservation 2011–2020. Secretariat of the Convention on Biological Diversity, Montréal and Botanic Gardens Conservation International, Richmond, UK. Technical Series No. 95.
SMITH, G. (2020). Vireyas in New Zealand. The New Zealand Rhododendron, 8: 52–57. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
SMITH, G. (2021). Frank Kingdon Ward Rhododendrons at Pukeiti. The New Zealand Rhododendron, 9: 32–34. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
THOMSON, D. (2015). Dunedin well placed to play a significant conservation role. The New Zealand Rhododendron, 3: 43–45. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
THOMSON, D. (2017). Rhododendron species collection verification. The New Zealand Rhododendron, 5: 22–25. Available online: www.pukeiti.com/newsletter-archive/ (accessed June 2026).
THOMSON, D. (2018). Partnering plants and people: the ARS/DRG joint convention, Bremen, 2018. The New Zealand Rhododendron, 6: 28–39. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
THOMSON, J. (2025). Rhododendron hunting in Nagaland and Arunachal Pradesh. The New Zealand Rhododendron, 13: 34–43.
WESTWOOD, M., CAVENDER, N., MEYER, A. & SMITH, P. (2020). Botanic garden solutions to the plant extinction crisis. Plants, People, Planet, 3(1): 22–32. https://doi.org/10.1002/ppp3.10134
WILKIE, M. (2023). Heritage Park, Kimbolton. The New Zealand Rhododendron, 11: 24–33. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
WILKIE, M. (2024). Tannock Glen: an air of quality. The New Zealand Rhododendron, 12: 2–23. Available online: www.pukeiti.com/newsletter-archive (accessed June 2026).
Downloads
Published
Issue
Section
License
Copyright (c) 2026 Marion MacKay
This work is licensed under a Creative Commons Attribution 4.0 International License.
Please read our Open Access, Copyright and Permissions policies for more information.
