Two new species, three new records and taxonomic notes of Rhododendron (Ericaceae) in Thailand

Maneenuch Tubtamat; Santi Watthana; Trevor R. Hodkinson; Chalermpol  Suwanphakdee

doi:10.20531/tfb.2026.54.2.10

Authors

Maneenuch Tubtamat Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
Santi Watthana School of Biology, Institute of Science, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
Trevor R. Hodkinson Botany, School of Natural Sciences, Trinity College Dublin, Dublin D2, Ireland
Chalermpol Suwanphakdee Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand

DOI:

https://doi.org/10.20531/tfb.2026.54.2.10

Keywords:

anatomical features, Ericaceae, plant taxonomy, pollen morphology, Flora of Thailand

Abstract

Two new species, Rhododendron trichopetalum and R. yalaense, from Peninsular Thailand, are described and illustrated. Three new records of R. jasminiflorum, R. klossii and R. robinsonii are newly reported for Thailand, and R. klossii is herein reinstated. Lectotypifications were designated where required and an updated key to species, modified from the Flora of Thailand, is provided.

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Author Biography

Chalermpol Suwanphakdee, Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand

Palynology Special Research Unit, Department of Botany, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand

References

APG IV (2016). An update of the Angiosperm Phylogeny Group classification for the orders and families of flowering plants. APG IV. Botanical Journal of the Linnean Society 181: 1–20.

Argent, G. (2006). Rhododendron of subgenus Vireya. Royal Horticultural Society and the Royal Botanic Garden Edinburgh, 382 pp.

Argent, G., Lamb, A., Collenette, S. & Phillipps, A. (1988). Rhododendron of Sabah. Sabah Parks Trustees No. 8.

Bhattacharyya, D. & Sanjappa, M. (2008). Rhododendron habitats in India. Journal of American Rhododendron Society 62(1): 14–18.

Chamberlain, D., Hyam, R., Argent, G., Fairweather, G. & Walter, K.S. (1996). The genus Rhododendron: its classification and synonymy. Royal Botanic Garden Edinburgh, 181 pp.

Cullen, J. (2005). Hardy Rhododendron species: a guide to identification. Royal Botanic Garden Edinburgh. 496 pp.

Erdtman, G. (1960). The Acetolysis Method. A revised description. Svensk Botanisk Tidskrift 54: 561–564.

Fang, M., Fang, R.Z., He, M.Y., Hu, L.Z., Yang, H.B. & Chamberlain, D.F. (2005). Rhododendron. In: Z.Y. Wu, P.H. Raven & D.Y. Hong (eds.), Flora of China. Missouri Botanical Garden Press 14: 260–455.

Goetsch, L., Eckert, A.J. & Hall, B. (2005). The molecular systematics of Rhododendron (Ericaceae): A phylogeny based upon RPB2 gene sequences. Systematic Botany 30(3): 616–626.

Hesse, M., Zetter, R., Halbritter, H., Weber, M., Buchner, R., Frosch-Radivo, A. & Ulrich, S. (2009). Pollen Terminology: an illustrated handbook. Springer Vienna. 269 pp.

Hooker, W.J. (1850). Rhododendron jasminiflorum. Curtis’s Bot. Mag. 76: t. 4524.

Hutchinson, J. (1932). Rhododendron. In: W.G. Craib (ed.), Florae Siamensis Enumertio 2(1): 317–319.

Irving, E. & Hebda, R. (1993). Concerning the origin and distribution of Rhododendron. The American Rhododendron Society 47(3). https://scholar.lib.vt.edu/ejournals/JARS/v47n3/v47n3-irving.html

IUCN Standards and Petitions Committee (2024). Guidelines for Using the IUCN Red List Categories and Criteria. Version 16. Prepared by the Standards and Petitions Committee. https://www.iucnredlist.org/documents/RedListGuidelines.pdf.

Johansen, D.A. (1940). Plant microtechnique. McGraw-Hill, New York, 523 pp.

Kermanee, P. (2008). Plant microtechnique. Kasetsart University Press, Bangkok [in Thai].

Linnaeus, C. (1753). Species plantarum, Stockholm: Laurentii Salvii.

Park, J. & Song, U. (2010). Pollen morphology of the genus Rhododendron (Ericaceae) in Korea. Journal of Korean Society of Forest Science 99(5): 663–672.

POWO (2025). Plants of the World Online, Facilitated by the Royal Botanic Gardens, Kew. Published on the Internet: https://powo.science.kew.org/. (accessed on 10 August 2025).

Ridley, H.N. (1909–1911). The Flora of the Telom and Batang Padang Valleys. Journal of the Federated Malay States Museums, Kuala Lumpur 4: 43–44.

Sleumer, H. (1949). Ein System der Gattung Rhododendron L. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 74: 511–553.

Sleumer, H. (1958). The genus Rhododendron L. in Indochina and Siam. Blumea 4(1): 39–59.

Sleumer, H. (1960). Florae Malesisnae precursores XXIII the genus Rhododendron in Malesia. Reinwardtia 5: 45–231.

Sleumer, H. (1963). Studies in the Flora of Thailand 21. Ericaceae (Incl, Vacciniaceae). Dansk Botanisk Arkiv 23(1): 79–81.

Sleumer, H. (1966). Ericaceae. In: C.G.G.J.van Steenis (ed.) Flora Malesiana, Series I, Wolters-Noordhoff, Groningen 6: 469–611.

Sleumer, H. (1969). Studies in the Flora of Thailand 58. Some Species of Flacourtiaceae and Ericaceae New to Thailand. Dansk Botanisk Arkiv 27(1): 87–90.

Stevens, P.F. (2004). Rhododendron. In: K. Kubitzki (ed.), Springer-Verlag Berlin Heidelberg, New York 6: 171.

Stuessy, F.T. (2009). Plant Taxonomy: the systematic evaluation of comparative data, Second edition. Columbia University Press. 568 pp.

Suwanphakdee, C., Jarupund, P. & Hodkinson, T.R. (2026). Systematic Assessment of Thunbergia (Acanthaceae) From South East Asia Using Pollen Morphology. Palynology 50(3). https://doi.org/10.1080/01916122.2026.2642020.

Thiers, B. (2015, continuously updated). Index Herbariorum. The New York Botanical Garden, New York. Available at http://sweetgum.nybg.org/science/ih/. (accessed on 10 August 2025).

Walton, A.M., Halfacre, R.G. & Osborne, J.C. (1967). A Rapid Method for Preparation of Plant Material for Paraffin Embedding. Journal of the American Society for Horticultural Science Hort 2(3): 116.

Watthana, S. (2015). Rhododendron. In: T. Santisuk & H. Balslev (eds.), Flora of Thailand. The Forest Herbarium, Department of National Parks, Wildlife and Plant Conservation, Bangkok, Thailand 13(1): 125–132.

WFO (2025). World Flora Online. Published https://www.worldfloraonline.org/ (accessed on 10 August 2025).

Xia, X.M., Yang, M.Q., Li, C.L., Huang, S.X., Jin, W.T., Shen, T.T., Wang, F., Li, X.H., Yoichi, W., Zhang, L.H., Zheng, Y.R. & Wang, X.Q. (2022). Spatiotemporal evolution of the global species diversity of Rhododendron. Molecular Biology and Evolution 39(1): msab314. https://doi.org/10.1093/molbev/msab314