Hydrangea hydrangeoides Concolor Form — Greenback hydrangea vine

Introduction

The Concolor Form is Tree TSAR's editorial treatment of the Japanese foliage variant historically known as Schizophragma hydrangeoides var. concolor Hatus., later S. hydrangeoides f. concolor (Hatus.) H.Ohba and, following transfer into broad Hydrangea, H. hydrangeoides f. concolor (Hatus.) J.M.H.Shaw. Current international backbones place all three names in synonymy under typical H. hydrangeoides var. hydrangeoides. Tree TSAR agrees that the entity does not require formal botanical rank, but retains it as a Form because it combines a recognizable wild phenotype with an unusually strong horticultural identity.

The underlying morphological distinction is subtle but intelligible. Typical Japanese H. hydrangeoides generally has leaves conspicuously paler or whitish beneath, whereas the historical concolor phenotype has foliage that remains greener on the lower surface; the upper surface is described as lustrous. This is essentially a foliage-color character rather than evidence for an independently evolving geographic lineage. No genomic, reproductive, or ecological differentiation corresponding to the concolor morphology has been demonstrated (Ohba 2001; Shaw 2012; Sutton 2025).

That would ordinarily make the entity little more than a useful synonym. Its horticultural history changes the calculation. The famous cultivar ‘Moonlight’ has long been associated with f. concolor, and both horticultural literature and databases continue to use the concolor name in connection with it. ‘Moonlight’ is one of the most widely grown selections of the species in North America and Europe. Its leaves show conspicuous silver-gray shading or mottling above with green veins, giving the plant much of its ornamental value even outside the flowering season (Shaw 2012; Sutton 2025).

Tree TSAR therefore uses Concolor Form as a narrative bridge between wild botanical variation and horticultural usage. This does not mean that ‘Moonlight’ is synonymous with the Form, nor that every plant displaying silver foliage represents the original concolor phenotype. ‘Moonlight’ remains a cultivar. The Form page instead preserves the historical biological concept with which that cultivar has repeatedly been associated and provides a place to explain the distinction.

This treatment also illustrates why a Tree TSAR Form is not simply another taxonomic rank. The Concolor Form is not proposed as a discrete evolutionary lineage and would not score highly under the usual genomic, geographic, or ecological axes. It receives a page because the phenotype is historically named, recognizable, and exceptionally prominent in horticulture. Were the horticultural history absent, the same level of differentiation would probably remain ordinary species-level variation.

Horticultural and Agricultural Uses

Horticultural significance is the principal reason the Concolor Form merits dedicated treatment. ‘Moonlight’ was selected from Japanese wild material collected by American plantsman Barry Yinger in 1974 and has become one of the best-known ornamental schizophragmas. Its foliage develops a striking silver-gray cast between green veins, giving the vine a distinctive appearance for much of the growing season. Sutton describes it as among the most widely grown cultivars of the species in North America and Europe.

The connection between ‘Moonlight’ and historical f. concolor should nevertheless be expressed carefully. Horticultural authors have placed the cultivar within concolor, but the ornamental silvering of the upper surface is not identical to the original taxonomic distinction, which primarily concerns the greener lower surface. Tree TSAR therefore treats ‘Moonlight’ as an associated cultivar, not as the definition of the Form.

This separation is useful for database interoperability. Historical botanical names can remain searchable under the Concolor Form, while cultivated selections remain cultivars rather than being mistaken for botanical taxa.

Conservation Concerns

The Concolor Form has no independent formal conservation status and is not known to represent a geographically isolated population. Its significance lies primarily in preservation of a recurring phenotype and its horticultural history rather than a separately threatened evolutionary lineage.

For wild conservation purposes, the most useful action is to retain locality information on herbarium specimens and wild-origin accessions showing the concolor phenotype. If future sampling finds that greener-backed plants are geographically or genetically structured, the interpretation could be revisited. In the absence of such evidence, the Form should remain explicitly subordinate to the broader Japanese population of H. hydrangeoides.

Cultivated abundance of ‘Moonlight’ likewise should not be interpreted as ex situ conservation of the original wild concolor concept unless the relationship between the cultivar and that phenotype can be demonstrated more precisely.

Additional Information

Plants of the World Online — Hydrangea hydrangeoides var. hydrangeoides (opens in a new tab): Plants of the World Online — historical concolor names currently synonymized under var. hydrangeoides.

Trees and Shrubs Online — Hydrangea hydrangeoides (opens in a new tab): Trees and Shrubs Online — morphology of f. concolor and the horticultural history of ‘Moonlight’.

References and Further Reading

Ohba H (2001) Deinanthe, Schizophragma, Pileostegia, Hydrangea, Cardiandra, and Platycrater. In: Iwatsuki K, Boufford DE, Ohba H (eds.) Flora of Japan, vol. IIb. Kodansha, Tokyo, pp. 83–96. https://www.kspub.co.jp/book/detail/1546059.html (opens in a new tab)

Royal Botanic Gardens, Kew (2026) Hydrangea hydrangeoides var. hydrangeoides. Plants of the World Online. https://powo.science.kew.org/taxon/urn:lsid:ipni.org:names:3297484-4 (opens in a new tab)

Shaw JMH (2012) Climbing hydrangeas and their relatives. The Plantsman, New Series 11(4): 226–231. https://www.rhs.org.uk/about-us/pdfs/publications/the-plant-review/general-pdfs/index-for-2012.pdf (opens in a new tab)

Sutton J (2025) Hydrangea hydrangeoides. Trees and Shrubs Online. International Dendrology Society. https://www.treesandshrubsonline.org/articles/hydrangea/hydrangea-hydrangeoides/ (opens in a new tab)