Ironwood

Fall color of ironwood.

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.

Botanical name:

Ostrya virginiana

All Common Names:

ironwood, American hophornbeam, eastern hophornbeam, hop-hornbeam

Family (English):

Birch

Family (Botanic):

Betulaceae

Planting Site:

  • Residential and parks,
  • City parkway,
  • Wide median

Tree or Plant Type:

  • Tree

Foliage:

  • Deciduous (seasonally loses leaves)

Native Locale:

  • Chicago area,
  • Illinois,
  • North America

Landscape Uses:

  • Parkway/street,
  • Shade tree,
  • Specimen

Size Range:

  • Large tree (more than 40 feet),
  • Medium tree (25-40 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

Acid Soils:

  • Tolerant

Alkaline Soils:

  • Tolerant

Salt Spray:

  • Moderately Tolerant

Soil Salt:

  • Intolerant

Drought Conditions:

  • Tolerant

Poor Drainage:

  • Intolerant

Ornamental Interest:

  • Fall color,
  • Persistent fruit/seeds,
  • Attractive bark

Season of Interest:

  • Mid summer,
  • Late summer,
  • Early fall

Flower Color & Fragrance:

  • Inconspicuous

Shape or Form:

  • Pyramidal,
  • Round

Growth Rate:

  • Slow

Transplants Well:

  • No

Wildlife:

  • Browsers,
  • Small mammals,
  • Songbirds

More Information:

Tree & Plant Care

Full sun to partial shade, naturally occurs in dry woodland understory.

Best in slightly acid soil that is moist, fertile and  well-drained, can tolerate dry gravelly soils in partial shade once established.

Difficult to transplant and slow to establish.

Not tolerant of salt.

Prune in late winter or early spring.

Disease, pests, and problems

Not susceptible to any serious insect or disease problems

Native geographic location and habitat

C-Value: 5
Native to IL, Midwest and southeastern U.S.

Bark color and texture

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

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

Alternate, simple deciduous leaves, 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.  Fall color is yellow.

Flower arrangement, shape, and size

Male flowers are 1 inch long catkins. Female flowers small and inconspicuous

Fruit, cone, nut, and seed descriptions

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; fruit changes from green cream to tan.

Location of Ostrya virginiana (Ironwood) at the Arboretum