Common Name: Pagoda Dogwood (alternate-leaved dogwood) Family: Cornaceae Genus:CornusSpecies:alternifolia
Figure 2: Berries of pagoda dogwood. Retrieved from https://www.flickr.com/photos/ivantortuga/2239250557
Height: 15-25 feet Canopy Spread: 20-32 feet Stem Girth: <4 inches Life Expectancy: 25-50 years, up to 80 if well maintained Hardiness: Zones 3-8
Plant Description: A common understory species in Minnesota, pagoda dogwood is recognized by its broad, layered form. This has made it a popular ornamental shrub. Its maroon twigs, showy spring flowers, and brilliant autumn foliage certainly don't hurt matters. C. alternifolia is one of six Cornus species in Minnesota, and the only one that does not have opposite leaves. Look for leaves with deep green color, prominent, evenly spaced lateral veins, smooth edges, and noticeably pale undersides.
Figure 3: Pagoda dogwood form. Retrieved from https://commons.wikimedia.org/wiki/File:Cornus_alternifolia_-_Krauss.jpg
Site Characteristics: Prefers sites with deep, acidic, organically rich, well-drained soils. In residential areas, provide consistent moisture throughout the growing season. Full sun to partial shade is preferred, with shade being more important in hotter summer climates. Can grow as both an individual or as a part of a small group, typically the best growth will occur in partial shade and with wind protection. C. alternifolia is hardy through zones 3-8. In colder climates, applying mulch to the root zone to in winter may help to protect it, particularly in exposed locations. The growing season extends from early to mid spring, until late fall. It can be planted at either end of the growing season. As a residential tree, it can be grown on any side of the yard, though different locations may require different care. Locations with full sun will require more watering than shadier spots, and exposed trees may benefit more from mulching or artificial wind protection.
Uses: C. alternifolia is commonly used as an ornamental species in yards and parks, either as an individual or as part of a group. The showy spring flowers and dark green leaves are aesthetically appealing, as is the full, tiered branching pattern. The fruit attracts wildlife species such as birds to the area, and pollinators will be attracted to the fragrant flowers. It has reddish to yellowish fall foliage. The spring flowers and overall shape of the pagoda dogwood, as well as the brilliant fall color, makes it a year-round interest.
Figure 4: Pagoda Dogwood Range Map. Retrieved from https://www.fs.fed.us/database/feis/plants/shrub/coralt/all.html
Range: Native to the Eastern parts of North America, C. alternifolia performs best in acidic, rich, well-drained soils. Cooler summer climates are preferred, though it can do well in hotter temperatures if adequate shade is provided. It can be found both within forests as well as on the forest edges, in either moist or dry soils. It is also often found in open fields or along stream banks.
Planting and Maintenance: Can be planted in either early-mid spring or late fall. Little maintenance is required. If pruning is needed, it should be done in early spring before the plant leafs out. Pruning of the lower branches during dormancy can be used to create more of a tree shape rather than the typical shrub form.
Reproduction: Pagoda dogwood is a dioecious plant, with flowers containing both male and female parts. It is self-fertilizing, allowing it to continue to produce large amounts of fruit even when no other dogwoods are nearby. It is spring flowering, with blooms typically occurring between May and July. The fruits, small blue/black drupes, usually ripen in July. C. alternifolia may be vegetatively propagated. Reproduction may occur though layering, root-crown sprouting, and seed. Embryo dormancy delays germination.
Figure 5: Golden Stem Canker. Retrieved from https://hort.extension.wisc.edu/articles/golden-canker-cryptodiaporthe-canker/
Golden Stem Canker: The Cryptodiaporthe canker, or golden stem canker, is a disease that causes significant problems for C. alternifolia. An infection by the fungus can be lethal, particularly if it's lcoated in the main stem of the tree. The distinct yellow cankers on the stem and branches make this disease easy to identify.
The best way to reduce the risk of a Cryptodiaphorthe infection is to keep tree stress to a minimum. For alternate-leaved dogwoods, this means appropriate planting location (cool, moist, shady), and providing adequate water. Pay close attention to drought conditions, as drought-stressed trees are the most susceptible. This is a common affliction of nursery-bought plants, and the purchase or planting of infected individuals should be avoided.