Arboretum: Flowering Dogwood hybrids
If you go to a garden center to buy a flowering dogwood tree, chances are you’ll find a selection tagged with names like Celestial, Stellar Pink or Constellation. These are hybrid dogwoods, crosses between our native Cornus florida and the Asian Cornus kousa. They’re the result of 20 years of breeding trials started in the 1970s at Rutgers University. Six in what are known in the trade as the Stellar© series have been patented, trademarked and DNA fingerprinted.
Their names are: ‘Ruth Ellen’, ‘Stardust’, ‘Celestial’, ‘Constellation’, ‘Aurora’, and ‘Stellar Pink’.
Each can grow up to approximately 20 feet tall and wide. Their floral bracts, or colored petals surrounding the small central flower, vary from white to versions of pink with a semi-pointed shape intermediate to both parents. The bloom time for these hybrid trees is between the early flowering of our native dogwood and the later flowering of the kousa dogwood. Each has a more open silhouette and bears fewer flowers that our native dogwood.
What makes these six trees important, however, and so prevalent in nurseries and garden centers, is that they’ve inherited from the kousa parent a high resistance to borer damage, anthracnose disease and powdery mildew. Many of our native dogwoods are plagued by all three.
As May arrives, the blooms of the Stellar© dogwoods are just beginning to appear here on campus at Haverford College. They’re ready to take center stage as our native dogwoods pass their peak, and before their Asian parents burst into color.
~ Martha Van Artsdalen