Hydrangea ampla Choufenianum Form — Choufen hydrangea vine

Introduction

The Choufenianum Form represents a historically named regional expression of Hydrangea ampla centered on the concept originally described by W.Y. Chun as Schizophragma choufenianum. Tree TSAR does not recognize it as a formally ranked botanical taxon. Instead, it is treated as a Form because the original plant appears to represent a morphologically and geographically interesting component of H. ampla that deserves continued documentation, while the evidence presently available is insufficient to demonstrate the independence expected of a species, subspecies, or variety.

Chun's species was described from northeastern Guangxi, and Flora of China records it from Lingui in moist valley forest and rocky habitats at about 600 m. The historical diagnosis emphasizes elliptic leaves 14–19 cm long, pubescence concentrated along the lower leaf veins but becoming reduced with age, and especially small obconical capsules approximately 4–5 mm long whose apices are truncate rather than conspicuously projected. Significantly, the fertile flowers were still unknown in the Flora of China treatment (Chun 1954; Wei & Bartholomew 2001).

Those characters were sufficient for Flora of China to maintain S. choufenianum as a species and to distinguish it from S. integrifolium primarily through capsule shape. The later revision of Liu & Zhu (2011), however, recognized only seven species in Schizophragma and did not retain choufenianum at species or infraspecific rank. Sutton (2025) likewise places it within the broader H. ampla problem rather than treating it as an independently demonstrated species.

The Tree TSAR Form treatment is intended to preserve exactly this intermediate state of knowledge. The truncate-fruited Guangxi morphology may represent localized genetic differentiation, an ecologically associated population, an extreme within ordinary H. ampla variation, or some combination of these. No population-genomic study has yet tested those alternatives. Suppressing the name entirely would make that uncertainty difficult to communicate, while restoring species rank would imply a degree of evolutionary independence that has not been demonstrated.

The name has also remained relevant beyond herbarium taxonomy. Crûg Farm has cultivated a northern Vietnamese collection, FMWJ 13217, under the provisional identification Schizophragma aff. choufenianum. That plant was collected in the Hoang Lien Son mountains and differs enough from familiar cultivated schizophragmas to have attracted horticultural attention. Its tentative identification should not be used to extend the range of the Guangxi Choufenianum Form into Vietnam: the collection has not been demonstrated to belong to Chun's entity and could instead represent another expression of H. ampla or even an undescribed lineage. Its importance here is that it shows the choufenianum concept remains actively encountered when unusual wild-origin material is compared with existing names.

Horticultural and Agricultural Uses

The Choufenianum Form is not a mainstream ornamental entity, but it has unusual value to specialist collections because the name provides a historical reference point for uncommon mainland Asian climbing hydrangeas with atypical fruit and foliage. Plants distributed as Schizophragma aff. choufenianum, particularly FMWJ 13217, should retain their collection numbers and provisional identifications wherever possible. Such provenance information may eventually prove more useful than the name itself if molecular comparisons are undertaken.

The Tree TSAR Form concept is especially appropriate in this setting. It permits distinctive cultivated or wild-origin material to be discussed on a dedicated page without presenting all plants carrying the choufenianum label as one proven biological lineage. Horticultural material should therefore be compared against the original Guangxi morphology rather than assumed to represent it.

Conservation Concerns

Because the Choufenianum Form is a Tree TSAR editorial entity rather than a formally accepted taxon, it has no independent formal conservation assessment. The broad parent species H. ampla is not currently predicted to be globally threatened, but that says little about the persistence of a localized Guangxi morphotype.

The original choufenianum concept was geographically narrow, and the evidence reviewed here does not establish how common that morphology is today around Lingui or elsewhere in northeastern Guangxi. Field recollection from the type region is therefore a high priority. Flowering and fruiting specimens from multiple populations, combined with nuclear genomic sampling and comparison with nearby ordinary H. ampla, would determine whether the Choufenianum Form represents a localized but continuous variant, a structured population worthy of formal rank, or an entity that should ultimately disappear into ordinary species-level variation.

Until such evidence exists, conservation statements should focus on documenting and retaining geographically precise populations rather than assigning an unsupported threat category to the Form itself.

Additional Information

Flora of China — Schizophragma choufenianum (opens in a new tab): historical species description, morphology, and Guangxi distribution.

Trees and Shrubs Online — Hydrangea ampla (opens in a new tab): discussion of the taxonomic status of S. choufenianum.

Crûg Farm — FMWJ 13217 (opens in a new tab): Crûg Farm — Schizophragma aff. choufenianum FMWJ 13217: cultivated northern Vietnamese material provisionally compared with the historical species.

References and Further Reading

Chun WY (1954) A census and preliminary study of the Chinese Hydrangeoideae. Acta Phytotaxonomica Sinica 3(2): 101–205. https://cpni.ibiodiversity.net/26764 (opens in a new tab)

Crûg Farm Plants (n.d.) Schizophragma aff. choufenianum FMWJ13217. Online plant catalogue. https://mailorder.crug-farm.co.uk/default.aspx?pid=11852 (opens in a new tab) (accessed 8 October 2026).

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)

Sutton J (2025) Hydrangea ampla. Trees and Shrubs Online. International Dendrology Society. https://www.treesandshrubsonline.org/articles/hydrangea/hydrangea-ampla/ (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)