Hydrangea corylifolia (Chun) Y.De Smet & C.Granados — Hazel-leaf hydrangea vine

Introduction

The hazel-leaf hydrangea vine, Hydrangea corylifolia, is a deciduous, aerial-rooting woody climber of eastern China and one of the more geographically compact species in Section Schizophragma. It is securely recorded from Anhui and Zhejiang, where it grows in mixed forests in valleys and along streams from roughly 100 to 1200 m elevation. The species is distinguished especially by its relatively broad, often broadly ovate to suborbicular leaves, which are shallowly cordate to rounded at the base and coarsely serrate over the distal portion of the blade. The lower leaf surface is villous primarily along the veins rather than densely tomentose throughout, providing another useful distinction from H. schizomollis (Wei & Bartholomew 2001; Liu & Zhu 2011).

That combination of leaf shape and marginal serration gives H. corylifolia a reasonably practical identity within an otherwise difficult group. Typical H. ampla usually has entire or only weakly toothed leaves, while H. glaucescens is characterized more strongly by its pale or glaucous lower leaf surface and tufts of hairs in the vein axils. The broadly hazel-like foliage of H. corylifolia therefore represents more than the minor quantitative variation that has complicated several other species concepts in the section. Sutton's synthesis accordingly treats the species as a recognizable eastern Chinese entity and notes that plants cultivated under this name have not always been correctly identified.

Its nomenclatural history is remarkably compact by the standards of Section Schizophragma. W.Y. Chun described the species as Schizophragma corylifolium in 1954. A later Chinese name, S. integrifolium f. cordatum S.Y.Wang, was based on material interpreted as part of the much broader integrifolium complex. Liu & Zhu (2009), after examining type and authoritative specimens and comparing leaf-epidermal characters, concluded that the latter belonged within S. corylifolium. Current Kew taxonomy agrees, recognizing only these two earlier names beneath Hydrangea corylifolia (Liu & Zhu 2009; Royal Botanic Gardens, Kew 2026).

The available molecular evidence is compatible with species recognition but should not be overstated. Yang et al. (2024) included H. corylifolia in their broadly sampled plastome-based reconstruction and retained it within a coherent Section Schizophragma. Their study was designed to establish infrageneric relationships rather than population-level species limits, however, so the principal support for the present species concept remains the combination of morphology, eastern Chinese geography, and the focused taxonomic work of Liu & Zhu. More extensive nuclear sampling would be welcome but is not presently needed to justify continued recognition.

Horticultural and Agricultural Uses

Hydrangea corylifolia appears to be extremely uncommon or absent from verified Western cultivation. Sutton reports no securely identified cultivated plants and notes that material carrying the name has sometimes proved to be something else. This is significant in a group where horticultural collections have historically circulated under broad or outdated Schizophragma names and where vegetative similarity makes misidentification easy.

The species nevertheless has clear ornamental potential. Its relatively coarse, serrated foliage provides a visual distinction from the more familiar H. ampla, while the deciduous self-clinging architecture and sterile flowers with a single enlarged sepal retain the characteristic appearance of Section Schizophragma. Any future introduction from Anhui or Zhejiang should retain collection locality and voucher information carefully. Authenticated living material could contribute as much to systematic study as to horticulture, particularly because the species is currently poorly represented outside its native range.

Conservation Concerns

No formal global conservation assessment was located for Hydrangea corylifolia. Its documented distribution is substantially narrower than that of H. ampla or H. schizomollis, being centered in Anhui and Zhejiang, but a restricted provincial range alone does not demonstrate rarity or decline. Current floristic accounts place it in mixed forests along streams and valley systems from low to moderately high elevations (Wei & Bartholomew 2001; Royal Botanic Gardens, Kew 2026).

The most important conservation need is therefore basic resolution of its modern distribution and population abundance. Because the species is not well established in ex situ collections, loss of wild populations could not be assumed to be offset by horticultural representation. Verified occurrence records, population surveys, and collection of well-documented ex situ material would substantially improve the basis for future assessment.

Additional Information

Plants of the World Online — Hydrangea corylifolia (opens in a new tab): accepted nomenclature, synonymy, and distribution.

Flora of China — Schizophragma corylifolium (opens in a new tab): morphology, habitat, elevation, and historical Chinese treatment.

Liu & Zhu (2009) (opens in a new tab): type-based resolution of S. integrifolium f. cordatum into S. corylifolium.

References and Further Reading

De Smet Y, Granados Mendoza C, Wanke S, Goetghebeur P, Samain M-S (2015) Molecular phylogenetics and new (infra)generic classification to alleviate polyphyly in tribe Hydrangeeae (Cornales: Hydrangeaceae). Taxon 64(4): 741–753. https://doi.org/10.12705/644.6 (opens in a new tab)

Liu W, Zhu X-Y (2009) The identity of some taxa of Schizophragma (Saxifragaceae). Journal of Systematics and Evolution 47(2): 151–161. https://doi.org/10.1111/j.1759-6831.2009.00014.x (opens in a new tab)

Liu W, Zhu X-Y (2011) Leaf epidermal characters and taxonomic revision of Schizophragma and Pileostegia (Hydrangeaceae). Botanical Journal of the Linnean Society 165(3): 285–314. https://doi.org/10.1111/j.1095-8339.2010.01101.x (opens in a new tab)

Royal Botanic Gardens, Kew (2026) Hydrangea corylifolia (Chun) Y.De Smet & C.Granados. Plants of the World Online. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:77152137-1 (opens in a new tab)

Wei Z, Bartholomew B (2001) Schizophragma Siebold & Zuccarini. In: Wu ZY, Raven PH (eds.) Flora of China, vol. 8. Science Press, Beijing & Missouri Botanical Garden Press, St. Louis, pp. 408–410. https://www.iplant.cn/foc/pdf/Saxifragaceae.pdf (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)