Ostrya virginiana (Ironwood)
| Also known as: | American Hop-hornbeam, Eastern Hop-hornbeam |
|---|---|
| Genus: | Ostrya |
| Family: | Betulaceae (Birch) |
| Life cycle: | perennial woody |
| Origin: | native |
| Habitat: | part shade, shade, sun; average to dry soil; hardwood forest, upland slopes, wooded bluffs, old fields |
| Bloom season: | April - May |
| Plant height: | 20 to 50 feet |
| Wetland Indicator Status: | GP: FACU MW: FACU NCNE: FACU |
| MN county distribution (click map to enlarge): |  |
| National distribution (click map to enlarge): |  |
Pick an image for a larger view. See the glossary for icon descriptions.
Detailed Information
Flower: 
![[photo of winter male catkins]](/udata/r9ndp23q/pd3/ostrya-virginiana-798-1.jpg)
Male and female flowers are borne separately on the same tree (monoecious) in dangling clusters called catkins. Male catkins are in groups of 1 to 4 from the tips of 1-year-old branchlets, ¾ to 2¼ inch long, developing in fall, the flowers an appressed, reddish-brown scale-like bract that turns greenish and expands out in spring.
![[photo of female catkin]](/udata/r9ndp23q/pd3/ostrya-virginiana-6784326-2.jpg)
Female catkins are 1/8 to ½ inch long at the tips of first year branchlets, the flowers with a spreading, green bract and thread-like red styles.
Leaves and bark:
![[photo of leaves]](/udata/r9ndp23q/pd3/ostrya-virginiana-003.jpg)
Leaves are simple and alternate, soft to the touch, the blade oval-elliptic, 2 to 5 inches long, 1 to 2 inches wide, tapered to a pointed tip, the base rounded and symmetrical, sharply double-toothed along the edges. The upper surface is dark green with fine, velvety hairs, lower surface lighter green, hairy, especially along the veins, with tufts of hairs in vein axils. Leaf stalks are hairy, often glandular hairy.
![[photo of twig]](/udata/r9ndp23q/pd3/ostrya-virginiana-bud-15-3.jpg)
Twigs are brown to reddish with downy hairs and scattered white lenticils (pores), are often glandular hairy, and become smooth the second year.
![[photo of mature trunk]](/udata/r9ndp23q/pd3/ostrya-virginiana-798.jpg)
Older bark is grayish brown, thin and finely textured with vertical, rectangular plates. Trunks can reach 14 inches diameter.
Fruit:
![[photo of mature fruit]](/udata/r9ndp23q/pd3/ostrya-virginiana-827987.jpg)
The fruit is a small, oval nutlet enclosed in an inflated, papery sac 1/3 to 1 inch long. The mature fruiting catkin is similar in appearance to those of hops with a number of sacs in a pendulous series 1¼ to 2 inches long.
Notes:
Ironwood is a common understory tree throughout Minnesota's upland deciduous forest. Highly shade tolerant, it is slow growing in understories where it rarely grows into the canopy. Its branches are often broadly horizontal and retained fairly close to the ground. In open sunnier sites it can grow quite quickly, attaining a height of some stature. While most often it has only a single trunk, its not uncommon to find multi-trunked specimens with a broad, spreading crown. Its name of Ironwood comes from its extremely hard, durable wood. Like our oak species, it typically retains a number of dried brown leaves through the winter months, which is termed marcescent. Ironwood is an excellent small, urban shade garden species.
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More photos
Ironwood tree
Ironwood tree in fall color
Ironwood branches
fruiting branches
hairy new leaves emerging in spring
Ironwood tree
Ironwood tree in fall color
Ironwood branches
fruiting branches
hairy new leaves emerging in springPhotos courtesy Peter M. Dziuk taken in Anoka, Hennepin, Ramsey and Wright counties.
Comments
Have you seen this plant in Minnesota, or have any other comments about it?
on: 2017-04-19 07:13:43
Came home to find a freshly planted ironwood tree on the boulevard (4-18-17, Cooper neighborhood). The city of Mpls is replacing Ash trees infected by the emerald ash borer. This field guide provides a great introduction to a welcome neighborhood addition.
on: 2018-06-18 21:51:01
Near the lake interspersed among the White Pines
on: 2018-08-03 23:22:14
We have ironwood trees in the understory of our 15 acre woods on the lakeshore. Our woods are primarily aspen interspersed with birch, white and red oak, maple, basswood, eastern white pine. I have not observed any large ironwoods but would like to encourage some that we have to grow larger by opening the spaces around them. I find the horizontal branching and fruiting catkins very attractive.
on: 2018-09-21 08:41:27
I would like to post pictures of the most incredible ironwood clusters I have ever seen. Can I get some help to share these?
on: 2018-09-21 17:46:52
Kim, you could post them on the Minnesota Wildflowers Facebook page.
on: 2018-11-08 23:51:33
Occasional in the tall shrub layer in mixed red oak-sugar maple-basswood-aspen forests.
on: 2019-03-07 08:45:12
Understory trees 1-4m tall in upland (hilly) site, 16 of 55-09w, with bigtooth and quaking aspen, balsam fir, spruce. ID based on twigs and persistent dead leaves.
on: 2020-02-13 02:13:58
We have a number of these... love the bark.
on: 2021-05-18 07:33:24
Ordered 10 from St Louis County Native Tree Sale some 10 years ago and planted in our yard and neighbor's. Doing well
on: 2021-08-14 11:57:36
We live next to a large wooded area. We have a lot of Ironwood trees around us. Over just the past two or three months, many of these Ironwoods have died. Several others now have branches that are withering and appear likely to die too. We are saddened to be losing these wonderful trees. Is it related to the drought? Or might something else be going on? Any advice on how to evaluate and save our Ironwoods is immensely appreciated.
on: 2021-08-14 18:01:30
Mark, you should contact an arborist, or at least a Master Gardener.
on: 2021-09-21 18:51:42
I finally realized this is what I am seeing in our old pasture/oak savanna area, along with maples, basswoods and of course bur oaks. The main tree seems to be seeding 'babies' about 30 feet out from the main tree - is this normal/done by birds?
on: 2021-09-22 08:21:40
Renay, older ironwood trees have been known to root sucker, but seed also spreads by wind, water and critters.
on: 2022-03-01 11:18:45
I am considering planting 4 foot bareroot Ironwood trees in an area that gets sun and shade during the primary growing season. Our plan is to remove/kill established Buckthorn and use the Ironwood as replacement for both visual appeal and privacy. How far apart should I plant these 4 foot bareroot Ironwood so they both flourish and screen? Thanks!
on: 2022-03-01 12:28:38
D Haeg, I suggest consulting with the nursery that is supplying the ironwood.
on: 2022-04-18 14:51:23
About 10 years ago I noticed a tree in Duluth on the West side of Swan Lake Rd, that was just loaded with BRIGHT WHITE flowers that on close inspection, looked like "Hops" flowers. I had walked along that road for many years and had never seen ANY flowers there. I looked it up and identified it as a Hophornbeam. In all the years since then, it hasn't put on a display like that one year. Most years the tree doesn't even seem to flower, though last summer it flowered with fewer flowers that weren't very white so they were barely noticeable near the edge of the Maple / Basswood forest. People are currently tapping the nearby Maple trees to make Maple syrup.