Hydrangea moellendorffii
Chinese herb hydrangea
Synonyms
- Cardiandra alternifolia subsp. moellendorffii ()
- Cardiandra alternifolia var. moellendorffii ()
- Cardiandra moellendorffii ()
- Cardiandra sinensis var. moellendorffii ()
- Cardiandra laxiflora
- Cardiandra moellendorffii var. laxiflora ()
- Cardiandra sinensis
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Introduction
The Chinese herb hydrangea, Hydrangea moellendorffii, is the geographically broadest of the southern Cardiandra species, occurring from southern China to Iriomote in Japan's southern Ryukyu Islands. It is a perennial subshrub and is usually characterized by marginal flowers with two enlarged petaloid calyx lobes, contrasting with the usual three of H. alternifolia and H. marunoi and the absence of enlarged lobes in H. amamiohsimensis. POWO treats H. moellendorffii as a single species across this range (Royal Botanic Gardens, Kew 2026).
Modern genomic evidence has clarified its relationship to the southern Japanese island taxa, but not every part of its broad range equally well. In Tagane et al.'s (2022) MIG-seq analysis, sampled H. moellendorffii grouped closely with H. amamiohsimensis, and that lineage in turn was closely associated with H. marunoi. These results help explain why H. marunoi is genetically less closely associated with the superficially similar H. alternifolia than its flowers suggest.
The broad Chinese circumscription nevertheless deserves continued testing. The species has accumulated names including Cardiandra sinensis, C. laxiflora, C. moellendorffii var. laxiflora, and combinations treating it beneath C. alternifolia. POWO currently places all seven such names in synonymy under H. moellendorffii. Plants of the World Online (opens in a new tab) That treatment is reasonable for Tree TSAR at present, but dense nuclear sampling across China and the isolated Iriomote population remains a useful review trigger rather than assuming that limited genomic sampling has demonstrated complete range-wide uniformity.
Horticultural and Agricultural Uses
Chinese herb hydrangea remains chiefly a specialist collection plant. Like its close southern relatives, it is associated at least in the Ryukyus with humid, shaded stream environments and lends itself to woodland or ravine-style cultivation where moisture can be maintained.
Its unusually broad geographic span makes provenance especially valuable. A plant from Iriomote and one from continental China may both bear the same accepted species name while representing widely separated parts of its evolutionary and geographic history. Botanical collections should therefore retain locality information rather than allowing all cultivated material to merge into an anonymous horticultural pool.
Conservation Concerns
A single conservation designation cannot safely be generalized across the whole China-to-Iriomote range. In Japan, the Ministry of the Environment's 2025 Fifth Red List treats Cardiandra moellendorffii as Vulnerable (VU). The assessment applies to the Japanese component under the generic name used by that authority, not automatically to the species throughout China. Ministry of the Environment, Japan (opens in a new tab)
The isolated Iriomote occurrence is nevertheless of particular conservation and phylogeographic interest. Maintaining it in situ, together with well-documented ex situ accessions, preserves an island component of a lineage otherwise centered on the Asian mainland. Range-wide conservation interpretation will require comparable data from Chinese populations.
Additional Information
References and Further Reading
Ministry of the Environment, Japan (2025) Fifth Red List: Vascular plants. Ministry of the Environment, Tokyo. https://www.env.go.jp/nature/kisho/5th-rl-2025-book/01-5thredlist-vascularplant.pdf (opens in a new tab)
Setoguchi H, Yukawa T, Tokuoka T, Momohara A, Sogo A, Takaso T, Peng C-I (2006) Phylogeography of the genus Cardiandra based on genetic variation in cpDNA sequences. Journal of Plant Research 119(4): 401–405. https://doi.org/10.1007/s10265-006-0283-1 (opens in a new tab)
Tagane S, Fujii S, Hirota SK, Naiki A, Yahara T (2022) Hydrangea marunoi (Hydrangeaceae), a new species from Osumi Peninsula, southern Japan. PhytoKeys 211: 33–44. https://doi.org/10.3897/phytokeys.211.89452 (opens in a new tab)
Yang X, Xue T, Gao T, Liang Y, Smets EF, Gadagkar SR, Yu S (2024) An updated infrageneric classification based on phylogenomics and character evolution in Hydrangea (Hydrangeaceae). Taxon 73(2): 503–518. https://doi.org/10.1002/tax.13158 (opens in a new tab)