Common hackberry is a medium to large tree with a rounded crown, up to 90 feet tall.
Leaves are alternate, simple, with one side longer or wider than the other, sharply toothed, 2–4 inches long, with 3 main veins emerging from the base, tip sharply pointed, base uneven. Upper surface rough to the touch; lower surface hairy.
Bark is gray, rather smooth when young, becoming covered with distinctive corky, warty projections that eventually join into ridges with age.
Twigs are slender, usually shiny, flexible, zigzag, light brown, becoming gray. Pith is light colored and broken by intermittent chambers.
Flowers April–May; male flowers in clusters toward base of the new branch; female flowers toward the tip, small, single or in pairs.
Fruits in September, fleshy, berrylike, ¼–½ inch wide, orange red, ripening to deep purple, borne on long stems, with a single hard seed within, usually persisting through winter.
Similar species: Missouri has two other species of hackberries: sugarberry (C. laevigata) and dwarf hackberry (C. tenuifolia).
- Sugarberry has stout, spreading branches forming a broad, irregular crown; smooth bark that usually develops some warty projections; relatively narrower leaves than common hackberry, with a few teeth toward the tip. Leaves are smooth (not rough) on the upper surface; not hairy on the undersurface. Fruit are orange red to black, only to about ¼ inch wide. Occurs in the same kinds of habitats as common hackberry (bottomlands as well as uplands), with a slight preference for bottomlands. It is generally absent from the northern third of Missouri.
- Dwarf hackberry is a shrub to small tree up to 24 feet tall, often somewhat scraggly with some corky projections on the bark. Leaves are generally smaller than the other two hackberries and have few teeth. Fruit is orange to brown or red, to about ¼ inch wide. Occurs in rocky, open woods, dolomite glades, and along bluffs. It is generally absent from the northern third of Missouri as well as from the Bootheel.
Height: 90 feet; spread: 90 feet.
Habitat and Conservation
Occurs in moist woodlands, in bottomlands, and in uplands, nearly statewide. Although hackberry prefers moist bottom soil situations, it will grow on any moist, fertile area. Thick clusters of twigs ("witches' brooms") develop on many hackberries, especially ones growing in open areas. A mildew and a mite apparently cause the deformed buds that produce these variant growth patterns.
Until 2009, hackberry and other trees in its genus were placed in the elm family, the Ulmaceae. Nearly all books in print today reflect that understanding. However, scientists are using new tools to study plant relationships, particularly genetic (DNA) testing. In 2009, a group of respected botanists called the Angiosperm Phylogeny Group determined that hackberries are actually more closely related to cannabis and hops, so these are all now in the Cannabaceae, or hemp family.
Hackberry is used, though it is not a favorite plant, for landscaping and for wood products.
It has been used in shelterbelt plantings to form windbreaks.
Many Native American groups pounded the sweet fruits and used them to season meat and to make corn cakes tastier.
Hackberry leaves turn yellow in fall and are some of the first trees to start showing fall color. Look for them showing yellow color in low areas along streams in the second half of September.
The fruit is eaten by at least 25 species of songbirds, plus turkey, quail, grouse, squirrels, and raccoons. Flocks of cedar waxwings congregate to devour the fruits.
In springtime, hackberry psyllids (pron. SILL-ids), which are true bugs and (as adults) resemble tiny cicadas, lay their eggs on developing hackberry leaves. The leaves are suitable for their egg-laying for only a brief stage in their development in spring. The larvae hatch and begin to feed on the leaves; the growing leaf responds by forming a distinctive-looking gall around the feeding insects. These galls are called hackberry nipple galls, for their knobby appearance. In late summer or early fall, the adult psyllids emerge. The adults will overwinter in a protected place. Sometimes the adult psyllids can be very numerous in window screens in late summer. It might be annoying, but these insects are completely harmless. They can only survive on hackberry trees.