Can you explain an unusual phenomenon? I thought dogwood flowers had four petals, but I have seen a tree that has anywhere from four to six. Is this normal?
There are dogwood species, such as Cornus mas and Cornus sericea, that lack showy bracts, so I imagine you are looking at a species that develops flowers at the same time as leaves (the true flowers are tiny, and clustered in a button shape in the center of the bracts). Cornus florida ‘Appalachian Joy’ is an example of a dogwood that has supernumerary bracts. The number of bracts can be variable, as with Cornus nuttallii, which can have between four and eight unnotched bracts (the lack of notches distinguishes Pacific dogwood from Cornus florida).
Portland’s Hoyt Arboretum blog has a helpful post by taxonomist and herbarium curator Mandy Tu about types of dogwoods which should clarify some of the puzzling floral anatomy. About the species that bloom and leaf out at the same time, she explains that “the large showy ‘petals’ are actually involucral bracts (essentially a whorl of modified leaves) that have the appearance of flower petals! These bracts likely function to attract insect pollinators, as well as to protect the actual flowers.”
