Kendall County (IL) Forest Preserve District
Hop Hornbeam
(Ironwood)
Ostrya virginiana
[C-value
5]
Hazelnut family (Corylaceae)
Blooms
mid-April - mid-May
The native Hop-Hornbeam is common in our area. It prefers full sunlight to light shade, medium-moist to dry conditions. Habitats include upland deciduous woodlands, woodland edges and rocky wooded slopes. This medium-small tree may grow to 30' tall with a trunk 2' across. The alternate leaves are 3-5" long and 1½–2½" across, oval-shaped, doubly toothed, and tapering to a slender tip. Hop Hornbeam is usually monoecious - having both male and female flowers (catkins) on the same tree. The male catkins are 1-2" long, narrowly cylindrical and drooping down. The female catkins at the ends of branches are about ½" long. After pollination (by wind), the female flower begins to swell into a drooping compound fruit about 1½–2½" long and ¾–1" across that look like the fruit of a hop vine.
Hop Hornbeam fruit at Pickerill/Pigott Forest Preserve June 6, 2017
The nutlets of the fruit are enclosed in overlapping inflated sacs, somewhat flattened in shape, greenish white and later becoming dull brown.
Hop Hornbeam at Pickerill/Pigott Forest Preserve April 30, 2016 (female blooms at branch tips, one male catkin)
Hop Hornbeam female catkin developing fruit at Pickerill/Pigott Forest Preserve June 6, 2017
Hop Hornbeam trunk bark's narrow strips at Pickerill/Pigott Forest Preserve June 6, 2017
Hop Hornbeam wood is extremely dense and tough; hence, its other common name "Ironwood".
Hop Hornbeam maturing fall fruit (and seeds) at Pickerill/Pigott Forest Preserve September 5, 2006
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