Ostrya virginiana (Ironwood)
|Also known as:||American Hop-hornbeam, Eastern Hop-hornbeam|
|Life cycle:||perennial woody|
|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):|
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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.
Leaves and bark:
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.
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.
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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- Ironwood tree
- Ironwood tree in fall color
- Ironwood branches
- fruiting branches
- hairy new leaves emerging in spring
Photos courtesy Peter M. Dziuk taken in Anoka, Hennepin, Ramsey and Wright counties.
Have you seen this plant in Minnesota, or have any other comments about it?