Cornus × horseyi Rehder — Rochester dogwood

Introduction

Rochester dogwood (Cornus × horseyi) is a cultivated hybrid between silky dogwood (C. amomum) and bigleaf dogwood (C. macrophylla). It emerged from the remarkable Rochester Parks Department seed lot that also produced C. × dunbarii, and Rehder named the plant for Richard Horsey. The cross therefore joins an eastern North American wetland shrub with a large Asian forest dogwood within Subgenus Thelycrania (Deasy et al. 2026).

The hybrid can form a large, floriferous shrub and bears dark blue fruit. Its cultivated origin is essential to its interpretation: the parents do not meet in the wild, so the name represents a horticulturally created contact between otherwise allopatric lineages.

Horticultural and Agricultural Uses

Cornus × horseyi remains a specialist collection plant. Trees and Shrubs Online describes it as late flowering and capable of making a substantial shrub, but it has never become a mainstream ornamental (Deasy et al. 2026). Its greatest value is in arboreta that can maintain the historical record of the Rochester hybrids.

Vegetative propagation is the appropriate way to preserve a verified clone. Seed from the hybrid would segregate genetically and should not be assumed to reproduce the named nothospecies in the horticultural sense.

Conservation Concerns

Because Rochester dogwood is a cultivated hybrid, a wild conservation category is not applicable. Authenticated old clones are nevertheless worth preserving as part of horticultural history and as living evidence of reproductive compatibility among geographically separated members of Subgenus Thelycrania.

Additional Information

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

References and Further Reading

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

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