Description and habitat
Blue-beech or American hornbeam (Carpinus caroliniana) is a small tree or large shrub of moist deciduous forests. It is the only hornbeam native to North America, one of more than 25 species in the world. Blue-beech occurs in Ontario and Quebec south of the Canadian Shield and is widely distributed throughout the Eastern United States. In Canada, it is most often observed in the Lake Erie Lowland region of southwestern Ontario, or the “Carolinian Life Zone”.
Leaves are alternately arranged, 3-12 cm long, with toothed margins. Similarly to other members of the Birch family (Betulaceae), Blue-beech flowers consist of catkins that emerge in the spring. In the autumn, Blue-beech leaves turn a brilliant orange and yellow. The smooth, grey bark is one of the most important identification features – giving the tree its name, due it’s similarity to American Beech (Fagus grandifolia) bark. The bark also has smooth ridges that run vertically down the bark. The texture of these ridges, which is tough and muscle-like, giving the species a third common name, Musclewood. Blue-beech is most often observed in moist or wet forests, but it is typically intolerant of flooded conditions, thus it is absent from swamps. It often grows in the understory of maple (Acer sp.), beech, Basswood (Tilia americana) or oak (Quercus sp.) trees, alongside dogwoods (Cornus sp.), Red Elderberry (Sambucus racemosa), Spicebush (Lindera benzoin), Witch Hazel (Hamamelis virginiana), and Viburnums (Viburnum sp.).
Wildlife importance
The leaves and fruit of Blue-beech are highly important to wildlife. Nutlets are often consumed by small mammals and birds. The foliage is food resources to the larvae of the Io Silkmoth (Automeris io). Both the caterpillars and adult moths are toxic, having spiny projections that serve as stingers – a defensive mechanism. These moths can be green, yellow, and white, but they are dimorphic, with females being larger (7.5 cm in total wingspan, as opposed to ~6 cm for males). The entire lifespan of the Io Silkmoth occurs within several months, with adult moths flying for 1-2 weeks, solely with the function to reproduce.
Fun facts
- Blue-beech has a fairly dense branching structure, which is subtly layered. It’s horizontal branching and slightly zigzagging twigs give it a graceful form.
- Similarly to Hophornbeam (Ironwood), Blue-beech is an exceptionally strong hardwood, though economic uses are limited by this tree’s short size.
- Blue-beech frequently develops multiple stems arising from near the base. This is a common adaption to the low-light conditions among small, understory trees.
Written by Matthew Palarchio, HBSc in Environmental Sciences, Western University.
Photo Credits (L-R)
Growth Form © Matthew Palarchio
Bark © Ian Whyte
Leaves © Matthew Palarchio
Fruit Structure © Yann Kemper
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