Cornus × dunbarii Rehder — Dunbar dogwood

Introduction

Dunbar dogwood (Cornus × dunbarii) is a cultivated hybrid between eastern roughleaf dogwood (C. asperifolia) and Asian bigleaf dogwood (C. macrophylla). It arose at the Rochester Parks Department from a batch of C. macrophylla seed, with a North American dogwood growing nearby as the presumed pollen parent. Rehder later named the hybrid in honor of Rochester horticulturist John Dunbar (Deasy et al. 2026).

The plant combines traits of two geographically remote members of Subgenus Thelycrania. It can form a large shrub or small tree, flowers comparatively late, and produces blue fruit. Its history makes it one of the clearest demonstrations that cultivated proximity can create crosses that would never meet naturally.

Horticultural and Agricultural Uses

Cornus × dunbarii is principally an arboretum plant rather than a nursery staple. Trees and Shrubs Online records surviving material in important dendrological collections and notes a long flowering season extending from early summer into autumn in favorable conditions. That extended display, together with blue fruit, gives the hybrid real ornamental interest even though it remains uncommon (Deasy et al. 2026).

Propagation should be vegetative when the objective is to preserve the named hybrid genotype. Seedlings from a hybrid parent would recombine the genome and should not automatically be distributed as C. × dunbarii. Accurate accession history is therefore central to its horticultural identity.

Conservation Concerns

Dunbar dogwood is a cultivated hybrid and has no wild extinction status. Conservation is best understood as preservation of authenticated historical clones and their documentation. Old arboretum accessions can also serve as material for studying reproductive compatibility and trait inheritance within Subgenus Thelycrania.

Additional Information

Trees and Shrubs Online (opens in a new tab) - Detailed hybrid history, morphology, and cultivation account.
Plants of the World Online (opens in a new tab) - Kew search for the named hybrid.
International Plant Names Index (opens in a new tab) - Nomenclatural record search.

References and Further Reading

Deasy M, Crowley D, Aldridge J, Chişu R (2026) Cornus × dunbarii. Trees and Shrubs Online. https://www.treesandshrubsonline.org/articles/cornus/cornus-x-dunbarii/ (opens in a new tab)

Royal Botanic Gardens, Kew (2026) Cornus × dunbarii. Plants of the World Online. https://powo.science.kew.org/results?q=Cornus%20%C3%97%20dunbarii (opens in a new tab)

Du Z-Y, Xiang Q-Y, Cheng J, Zhou W, Wang Q-F, Soltis DE, Soltis PS (2023) An updated phylogeny, biogeography, and PhyloCode-based classification of Cornaceae based on three sets of genomic data. American Journal of Botany 110(2): e16116. https://doi.org/10.1002/ajb2.16116 (opens in a new tab)