By Dr. Bob Gilbert
We are so used to seeing our native Dogwood Cornus florida in the spring we tend to not recognize other native Dogwoods such as Cornus alternifolia (al-ter-ni-foli-a). There are two types of Dogwood blooms. Cornus florida has white petals more accurately called bracts with the true small yellow flowers in the middle. The other bloom type looks like Queen Anne’s Lace. These are technically called cymes, flat topped clusters of small cream to white colored flowers.
Cornus alternifolia is can be found in our woods here. This week I spotted one in Burningtown alongside a road. Most dogwood stems have leaves that are opposite to one another. This dogwood tree has alternate leaves, hence it species name. There is a West Coast dogwood called Giant Dogwood that can reach 45 feet. It also has alternate leaves. Horticultural folks have argued whether it is a true dogwood, hence its species name is Cornus controversa. The leaf veins of all dogwoods go all the way to the outer edge and join together or coalesce at the tip. Dogwood veins have an elastic material in them. If you gently pull a leaf apart the veins do not tear and the two parts stay attached to one another.
Cornus alternifolia is called Pagoda Dogwood. This name comes from branch growth patterns that layer horizontally in a whorled pattern all the way to the top like a pagoda. It can grow to 15-25 foot, likes high shade but can stand full sun. The blooms occur in May but do not catch your eye. The fruits are black and are favorite food for squirrels and Chipmunks. There are just a couple of cultivated varieties, the most popular being “Argentea,” which has brightly variegated leaves. Rich moist soil is what it likes best.
Cornus alternifolia is susceptible to a twig blight or a twig canker that causes a twig to turn yellow and die. Some horticulturists report that when a tree reaches 3-4 inches in trunk diameter the canker kills the entire tree. That was my experience at Smith-Gilbert Gardens. In 1985 I had planted a mail ordered Pagoda Dogwood in a location where I wanted a comfortable bench so I could sit and read under the branches. It took 10 years to create the desired effect and it was special. In about 2000 it just up and died. Previously there had been some twig die back, which I kept pruned off with sterile pruners using the dip in alcohol and cut technique. We all liked this tree so much we that we have allowed one shoot from the roots to grow and we are repeating the process. So this tree may only have a 15 to 20-year life expectancy? Recognizing that fact I would not hesitate to plant another, and would try to find the cultivar “Argentea.” On the Internet I found one that the nursery nicknamed the “Wedding Cake Tree.”
Dr. Bob Gilbert’s articles are being reprinted with the permission of the Franklin Press in Franklin, North Carolina.