Identifying characteristics:
The ironwood is a small, deciduous tree seldom taller than 30 feet (in Iowa)
with a rounded crown and slender branches. The leaves
are alternate, simple and 3 to 5 inches long, with petioles 0.25 inches
long. Leaves are thin but tough and are a dark, yellowish-green, turning
yellow in autumn and fading to brown-often persisting on the tree into winter,
especially on the lower branches. Distinctive tufts of hair appear in the
junctions of the main veins on the lower surface of the leaf. The flowers appear in spring, although immature
male flowers are present in catkins in winter. In spring, male flowers are
produced in these catkins at the ends of branchlets and female flowers are
produced in elongated clusters at the ends of new shoots. The fruit is a small, flattened nut enclosed in an
inflated, papery sac. A number of these sacs overlap in hanging clusters
1.5 to 2 inches long. These clusters closely resemble the fruit of the hop
vine used in brewing beer, hence the name "hophornbeam." The fruits
mature in autumn and drop in winter, leaving the axis attached to the tree.
The leaf scars are small and half-round, with 3 bundle scars. The
buds are ovoid, with 6 to 9 spirally arranged scales, creased with
vertical lines (viewed by hand lens). The bark
of the ironwood is smooth and gray or brown when young, becoming separated
into vertical, spiraled rows of small, rectangular plates that are sometimes
loose at both ends, producing a shreddy appearance.
Similar species:
- elms (Ulmus sp.) such as the American elm (Ulmus americana)
- bluebeech (Carpinus caroliniana)
- yellow birch (Betula alleghaniensis)
- serviceberry (Amelanchier sp.)
-
Ecology:
Distribution: The ironwood is native to southern Canada and eastern,
midwestern and south-eastern US, extending into northern Mexico. It is native
throughout Iowa and is probably the most common woodland tree in the state.
Habitat: Ironwoods grow in moist, fertile soils or in sandy soils, preferring well-drained slopes and ridges. This species is a typical understory tree preferring shade, but also grows well in full sun, often invading uncultivated areas bordering woods. Although a variety of diseases occasionally attack this tree diseases and pests are seldom problematic.
Uses:
Wood: "Ostrya" is Greek for "tree with tough wood."
The wood is harder than that of any other Iowa native tree, stronger than
that of white oak and second only to hickory in weight. The trees are too
small to be used commercially, however. This wood was once used for mallets,
levers, wedges, tool handles, ox yokes, wheels and axles. Ostrya makes excellent
firewood.
Wildlife: Birds and occasionally squirrels eat the nutlets; catkins are sometimes eaten by gamebirds and other animals; rabbits eat the bark and twigs.
Horticulture: Although Ostrya forms a handsome small tree, it has attracted little horticultural interest as the flowers are not showy, fall color is not spectacular and trees are slow to establish after transplanting.
