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Hydrangea crassa var. elliptica J.Anthony [TSAR]*

Elliptic-leaf hydrangea vine

Synonyms
  • Schizophragma crassum var. ellipticum J.Anthony
  • Schizophragma crassum var. hsitaoanum (Chun) C.F.Wei
  • Schizophragma hsitaoanum Chun
Suggest a Correction

Introduction

Elliptic-leaf hydrangea vine, Hydrangea crassa var. elliptica J.Anthony [TSAR]*, is Tree TSAR's formal varietal treatment of the northwestern Yunnan entity originally described as Schizophragma crassum var. ellipticum J.Anthony. Liu & Zhu (2009, 2011) concluded that var. ellipticum is the correct name for the same entity later called S. hsitaoanum Chun and S. crassum var. hsitaoanum (Chun) C.F.Wei. No validly published Hydrangea combination was located in the nomenclatural backbones reviewed, so Tree TSAR uses a provisional combination rather than presenting it as an ICN nomenclatural act.

Recognition at varietal rank reflects more than nomenclatural history. Flora of China distinguishes the Weixi plants from typical H. crassa by elliptic to narrowly ovate leaves, yellow-brown pubescence on the lower leaf surface, obliquely ascending secondary veins, and a broadly cuneate to obtuse leaf base. It also records the variety at approximately 2,600–2,900 m in Weixi, compared with typical H. crassa in the Nu Jiang valley at about 2,300–2,500 m. Liu & Zhu (2009, 2011) independently retained var. ellipticum after type and specimen study and found leaf-epidermal evidence consistent with the distinction.

Those morphological and geographic-elevational differences provide two partially independent axes of differentiation, enough for Tree TSAR to recognize a formal variety while stopping short of species rank. Nuclear population sampling has not yet demonstrated a fully independent evolutionary lineage, and current global backbones generally collapse the ellipticum and hsitaoanum names into undivided H. crassa. The variety is therefore accepted provisionally, with population-level genomic testing across northwestern Yunnan as the principal review trigger.

The accepted synonymy of the variety includes Schizophragma crassum var. ellipticum J.Anthony, Schizophragma hsitaoanum Chun, and Schizophragma crassum var. hsitaoanum (Chun) C.F.Wei. Historical determinations under any of those names remain useful because they can help relocate the morphologically coherent Weixi entity and test how sharply it intergrades with typical H. crassa.

A reliable field diagnosis should use the character combination rather than the epithet elliptica alone. Leaf outline overlaps with related material, but the combination of leaf shape and base, abaxial yellow-brown pubescence, venation, and the geographically and elevationally localized Weixi occurrence provides the strongest current basis for recognition.

Horticultural and Agricultural Uses

No substantial horticultural history has been located for H. crassa var. elliptica under any of its historical names. Its main value in cultivation would be scientific: authenticated, wild-provenance plants could test whether the leaf and epidermal distinctions documented from herbarium material remain stable across developmental stages and growing conditions.

Botanical collections should preserve historical labels such as S. crassum var. ellipticum, S. hsitaoanum, and var. hsitaoanum as determination history while using the current Tree TSAR varietal concept. Precise locality data are particularly valuable because geography and elevation are part of the evidence supporting the rank.

Conservation Concerns

Hydrangea crassa var. elliptica has no separate formal IUCN Red List assessment located in the sources reviewed. Its known Weixi occurrence is substantially narrower than the distribution of H. crassa as a whole, so conservation interpretation should not be inferred from the status of the broader species alone.

The immediate priority is to document the extent, abundance, and habitat condition of populations matching the elliptica concept and to preserve precise provenance in living and herbarium collections. If the variety is geographically coherent, loss of a small number of northwestern Yunnan populations could remove a disproportionate component of the species' recognized variation.

The principal re-review trigger is a study combining nuclear population genomics with quantitative morphology and leaf-epidermal data across typical H. crassa and the Weixi populations. Strong, geographically concordant differentiation could support higher rank; extensive genomic and morphological intergradation would argue for reducing the entity again.

Additional Information

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

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

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

Royal Botanic Gardens, Kew (2026) Hydrangea crassa (Hand.-Mazz.) Y.De Smet & C.Granados. Plants of the World Online. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:77152138-1

The Editors (1933) Diagnoses specierum novarum in herbario Horti Regii Botanici Edinburgensis cognitarum. DLI–DLXIX. Notes from the Royal Botanic Garden Edinburgh 18(86): 17–36. https://doi.org/10.24823/nrbge.1933.2377