Hackberry (Celtis occidentalis) is one of our most common trees in Iowa. Hackberry is a member of the elm family, but is a different genus. The name hackberry originated from the Scottish "hagberry" which in England was the common name bird cherry.
Habitat: Found on open lowland woods in moist disturbed soils
Hardiness: Zones 2 through 9
Growth Rate: Fast
Mature Shape: Cylindrical with drooping branches
Height: 40-60 feet
Width: 40-60 feet
Site Requirements: Prefers rich, well drained soil but adapts to a range of soil types. Plant in full sun.
Leaves: Alternate, simple, double-toothed with unequal leaf bases
Flowering Dates: April - May
Seed Dispersal Dates: October - Winter
Seed Bearing Age: 15 years
Seed Bearing Frequency: Yearly
Seed Stratification: Prechill for 3 months at 34°F to 40°F
Hackberry is easy to identify because of its distinctive characteristics of strongly unequal leaf base and rough, warty bark. The leaves are alternate, simple, 2-5 inches long, with strongly unequal bases and a sharply tapering tip. The leaf margin is toothed except near the base, lustrous to dull green above, with a fine network of veins below.
The twigs are slender, zigzag in appearance, light olive-brown in color with prominent lenticels. The pith of the twigs are usually chambered near the buds or nodes with small half-round leaf scars with usually three bundle scars. The terminal bud is absent; lateral buds are about 1/8 inch long, oval to triangular in shape, light brown in color, with 3-4 bud scales.
The bark is light to dark gray in color; on young trees the warty outgrowths appear to be scattered randomly while on older trees the warty outgrowths develop into narrow corky projecting ridges. The fruit is a dark purple drupe about 1/3 inch in diameter which is used by several species of birds including flickers, cardinals, cedar waxwings, brown thrashers, and robins. Hackberry has high wildlife value because the fruit persists into the late winter months.
Hackberry is native throughout Iowa. Hackberry grows in a wide variety of sites from dry and droughty to moderately moist to wet lowland sites. It probably does best on the moist sites and its common associates include green ash, silver maple, cottonwood, and boxelder on bottomland sites, and elms, walnut, and sugar maple on upland sites. On good sites, hackberry grows moderately fast; on dry sites, the growth rate is somewhat slower.
In Iowa, hackberry has two minor pest problems. Hackberry nipple gall, which are nipple-shaped outgrowths caused by a small insect are often unsightly but cause no damage to the tree. Hackberry also is susceptible to witches broom, a proliferation of small branches, also probably insect induced. Again, the damage to the tree in insignificant other than appearance of the tree. The witches brooms can be removed if desired.
Hackberry is a excellent ornamental tree for both street and landscape use. It grows moderately fast under most site conditions and generally tolerates adverse urban sites well. Hackberry is a moderately large tree (50-70 feet tall) and because of its vase-shape and rounded crown provides excellent shade. Fall color is yellow-green to yellow-brown.
The wood of hackberry is flexible, shock resistant and moderately strong, hard and heavy. It looks like elm but typically has a wider sapwood and distinctive yellow streaks. Its is used for pallets, furniture, and sporting goods.