These big, tough, fast-growing shade trees are similar to elms (Ulmus) but smaller. All have virtue of deep rooting; old trees in narrow planting strips expand in trunk diameter and nearly fill strips without surface roots or any sign of heaving the sidewalk or curb. Good choice for street or lawn tree, even near buildings or paving. Canopy casts moderate shade in spring and summer; leaves turn yellow in fall. Mature trees have picturesque gray bark with corky warts and ridges. Small, berrylike fruit attracts birds.
Hackberry is exceptionally durable, taking strong winds (stake young trees until well established); dry heat; and dry, alkaline soils. Bare-root plants, especially in larger sizes, sometimes fail to leaf out. Buy in containers or try for small bare-root trees with big root systems. Wholly optids, which look a bit like snowflakes, can be bothersome pests. They suck sap from the leaves and drip sticky honeydew on everything below. Black mold then grows on the honeydew. This doesn't harm the trees, but it makes a mess. Systemic insecticides applied soon after leaf-out provide control.
C. laevigata. SUGARBERRY, SUGAR HACKBERRY. Native to southern Midwest and South. Grows to 60 ft. or taller and equally wide, with rounded crown. Similar to C. occidentalis but resistant to witches' broom (ugly clusters of dwarfed twigs). This species is a desirable street or park tree.
C. occidentalis. COMMON HACKBERRY. Native from the Rocky Mountains to the Atlantic, north to Quebec and south to Alabama. Grows to form a rounded crown 50 ft. high or more and nearly as wide. Branches are spreading and sometimes pendulous. Oval, light green leaves are 25 in. long, finely toothed on edges. Leafs out fairly late. Withstands urban pollution. Widely used in plains and prairie states, since it endures adverse conditions, including extreme cold, wind, soggy soil. Sometimes disfigured by witches' broom. 'Prairie Pride' has handsome glossy leaves and a uniform habit; it is resistant to witches' broom.