Content Detail

Ironwood is a tough understory tree with beautiful birch-like leaves, grayish-brown flaky bark, fine-textured drooping branches, and attractive hop-like fruits. Ironwood is considered one of Illinois’ toughest native hardwoods and is not only ornamental but resistant to many disease and insect problems. Excellent tree for naturalized landscapes.

This species is native to the Chicago region according to Swink and Wilhelm’s Plants of the Chicago Region, with updates made according to current research.

  • Family (English) Birch
  • Family (botanic) Betulaceae
  • Planting site City parkway, Residential and parks, Wide median
  • Tree or plant type Tree
  • Foliage Deciduous (seasonally loses leaves)
  • Native locale Chicago area, Illinois, North America
  • Size range Medium tree (25-40 feet), Large tree (more than 40 feet)
  • Mature height 25-40 feet
  • Mature width 15-40 feet
  • Light exposure Full sun (6 hrs direct light daily), Partial sun / shade (4-6 hrs light daily)
  • Hardiness zones Zone 3, Zone 4, Zone 5 (Chicago), Zone 6, Zone 7, Zone 8, Zone 9
  • Soil preference Moist, well-drained soil
  • Tolerances Alkaline soil, Dry sites
  • Season of interest midsummer, late summer, early fall
  • Flower color and fragrance Inconspicuous
  • Shape or form Pyramidal, Round
  • Growth rate Slow
  • Transplants well No
  • Wildlife Browsers, Small mammals, Songbirds
  • Has cultivars Yes

Native geographic location and habitat:

Ironwood is native to Illinois, the Midwest and the southeastern United States. C-Value: 5

Bark color and texture:

The gray brown bark and trunk are ornamentally attractive, forming long vertical shredding strips.

Leaf or needle arrangement, size, shape, texture, and color:

The alternate, simple, deciduous leaves are 2 to 5 inches long and 1 to 3 inches wide. Medium to dark green leaves with doubly serrate leaf margins and a pointed leaf tip turn yellow in fall.

Flower arrangement, shape, and size:

The male flowers are 1 inch long catkins. Female flowers are small and inconspicuous.

Fruit, cone, nut, and seed descriptions: 

The fruit are drooping clusters at the tip of branches that look like hops, hence the common name hop hornbeam. Each small inflated sac has a hard nutlet inside. The fruit changes from green-cream to tan as it ages.

Plant care: 

Ironwood prefers full sun to partial shade. It naturally occurs in dry woodland understory areas. It does best in slightly acid soil that is moist, fertile and  well-drained, but can tolerate dry gravelly soils in partial shade, once it is established. It is difficult to transplant and slow to establish. It is not tolerant of salt. Prune it in late winter or early spring.

List of pests, diseases, and tolerances:

Ironwood is not susceptible to any serious insect or disease problems.

Donate

Your support is vital to the Arboretum, where the power of trees makes a positive impact on people’s lives.

Make a gift