The black gum (Nyssa sylvatica) is a deciduous tree that is originally from the United States. It is favored for its brilliant fall foliage and its winter form, which displays attractively dropping branches over time. Black gum is an excellent choice to add autumn color to your garden.
Nyssa sylvatica is the botanical name given to this species. The genus name of Nyssa is taken from a water nymph in Greek mythology. The family for black gum is Nyssaceae, though some botanists classify this genus within the Cornaceae (dogwood) family. The dove tree (Davidia involucrata) is also sometimes included in this family.
The names used for this tree are black gum, sourgum, yellow gum, black tupelo, cotton gum, tupelo-gum, pepperidge, swamp tupelo, swamp black gum, sour gum or tupelo. This tree is not related to gum trees, which belong to Angophora spp., Corymbia spp. and Eucalyptus spp.
Preferred USDA Hardiness Zones
Nyssa sylvatica is best suited for USDA plant hardiness zones 4 through 9. It is native to the eastern United States.
Size and Shape
The mature height of the black gum can be 30 to 75 feet tall and 20 to 35 feet wide, depending on the growing location and climate. When the black gum is young, it is usually formed into a pyramidal shape. Over the years it can be oval, irregular, or horizontal in shape.
The black gum should be planted where there will be full sun to part shade.
Foliage, Flowers, and Fruit
Nyssa sylvatica has dark green leaves that are ovate, obovate, or elliptical and measure 3 to 6 inches long. The fall display includes foliage in shades of orange, red, purple, and yellow. The flowers of black gum are light green in color and form into pendulous clusters in the spring.
Black gum trees generally are dioecious, so you would need both a male and a female for fruit production. Sometimes, however, the tree can grow perfect flowers, making this ultimately a polygamodioecious species. Once the flowers are pollinated, they form into black stone fruits (drupes) that mature in early fall. Birds will eat the fruits, but they are not desirable for human consumption.
Black Gum Varieties
‘Zydeco Twist’ is a variety of black gum that offers branches that twist somewhat and stand out during the winter. ‘Autumn Cascades’ is a weeping variety with especially good fall coloring. If you would like red leaves throughout the growing season, look for ‘Wildfire’.
Since the black gum has a long taproot, it can have difficulties after it is transplanted. It also may struggle if planted in the fall. For best results, you may want to start one from seed in the desired site or choose a young sapling where the taproot will be shorter.
Nyssa sylvatica needs soil that is acidic and that allows water to drain away from the roots. Reproduction is performed through seed germination and the use of cuttings. Grafting is used to preserve the characteristics of named cultivars.
Black gum does not usually require much pruning to maintain the tree beyond the standard care of removing parts that have become dead, damaged, or diseased.
Pests and Diseases
Black gum is vulnerable to specific pests and a few common diseases:
- The forest tent caterpillar (Malacosoma disstria) will chomp away at the leaves and cause defoliation. You can try organic controls like Bacillus thuringiensis var. kurstaki, neem oil, and spinosad. You can also remove affected branches to get rid of nests and eggs. If the problem persists and is extensive, call your local extension service to find appropriate insecticides for your area.
- Sapsuckers are a type of bird that peck holes into the trunk to reach the sap. You can wrap the areas of the trunk where they attack in burlap, or you can use a deterrent that is formulated for sapsuckers.
- Insect pests include sourgum scale (Chionaspis nyssae) and other scales and tupelo leafminer (Antispila nysaefoliella).
- Cankers can result when fungi start growing on a dead branch. Take out the affected branch to help curb the spread of the fungus.
- Heartrot occurs after a tree has had open wounds occur in the trunk. Fungi invade and, over time, cause the wood to rot and decay. You will need to watch the tree over time to see how extensive the damage becomes.
- Black gum is susceptible to leaf spots.
- Tupelo lesion happens when the Fusarium solani fungus attacks, resulting in the bark swelling up and becoming rough.