This unusual tree species belongs to the Dogwood family, Cornaceae. Other common names include sourgum, black tupelo, pepperridge, yellow gum, and swamp hornbeam. This tree can grow on moist sites along streams and in the uplands, but it grows best on welldrained, light-textured soils. It is tolerant of shade, and seems to grow more with the oak types than with the maples. The blackgum's unusual root system, similar to a multiple tap root, probably explains why the tree does better in deep, moist soils. Although very difficult to transplant, the blackgum is a beautiful ornamental tree and a very good food source for wildlife.
Cultivated in North America before 1750, the blackgum is found from Maine west to Michigan, south to Missouri, Oklahoma and Texas, back east to Florida, and up the coast again to Maine. Blackgum flowers are borne singly or in clusters; in Ohio, they bloom during May and June. Honeybees make a very fine honey from the flowers. Where the tree is common in the south, tupelo honey is often sold by name. The minute, greenish-white flowers may be perfect (containing both sexes), or staminate and pistillate flowers may be borne separately on different trees. The fruits ripen in September and October and fall from the tree soon thereafter. The fruit, an oblong drupe, is about onehalf inch long and is blueblack; the pit (seed) is indistinctly ribbed. It is edible, but if you eat one, you will quickly learn why it is called a sourgum.
Under natural conditions, seeds overwinter on cold moist soil and germinate in the spring. For seed collection, ripe fruits may be picked from the ground, from standing trees, or from felled trees and can be depulped by rubbing them over a large meshed screen. About 100 pounds of fruits will produce about 25 pounds of seed, which can be stored over the winter in moist cold sand or in refrigeration. Thirty to 120 days of stratification are needed to break seed dormancy. Plant the seeds onehalf to one inch deep. A thin mulch onequarter to one inch thick is helpful, since the seeds or seedlings can not be allowed to dry out. Blackgum requires nearly full sunlight for optimum growth.
The stately blackgum growing at the KCES can be found on the hillside behind the Visitor's Center. As seen from the butterfly garden, it stands the highest on the crest of the hill. Blackgum can grow to be 120 feet tall on the best sites. The branches are alternate with simple leaves that are shiny green above and paler and hairy underneath. The leaves turn a beautiful bright red in autumn, often contrasting with the green around the tree.
The greatest value of the blackgum tree is its use by wildlife for food and den sites. Because it is a prolific producer of cavities, blackgum is usually ranked as one of the more dependable den tree species. The list of animals that eat the fruits includes wild turkey, yellowshafted flicker, robin, brown thrasher, wood thrush, pileated woodpecker, gray squirrel, fox, raccoon, opossum, and chipmunk. The whitetailed deer and beaver browse the twigs and foliage.
Harold Bower,
ODNR Service Forester