Plant of the Week: Carpinus betulus; European Hornbeam
We’re not supposed to have favorites, but I can’t help it. My favorite tree in my garden is one I planted almost 25 years ago, a European hornbeam (Carpinus betulus). With Thanksgiving upon us, it is again bringing up the rear with its late season fall color display.
Carpinus belongs to the birch family and has about 40 species scattered throughout the Northern Hemisphere. This deciduous tree is native throughout much of Europe and bleeds over into Asia Minor where it occurs in mixed stands in hardwood forests.
European hornbeam in its native haunts can reach to 60 feet tall with a rounded to pyramidal form. As still a relatively young tree mine is about 28 feet tall and half as wide with a plump pyramidal form. Its lower branches are held out at almost right angles to the main trunk with its upper branches ascending, giving it a story book form I like to see in a tree. The trunk is the smooth gray of our native musclewood (C. caroliniana), but the European species does not have the same muscular appearance.
Hornbeams don’t have much going for them in the flower department, but their foliage effects are outstanding. They have deep green, symmetrical, toothy 2-inch-long leaves that are not bothered by drought, insect feeding or disease. In the fall, the trees are late to show fall color, always waiting well into November here in north Arkansas. Mostly my tree is a good clear yellow that sometimes tinges to orange.
When my tree starts flowering in the next few years, its male flowers will consist of 2-inch-long brownish catkins produced at the ends of the branches. The female flowers ultimately end in an open cluster of nutlets attached to three-lobed bracts that serve as wings and aid in seed dispersal. Flowers and fruit are mildly interesting but not beautiful.
I realize having a favorite tree that is foreign born puts me at odds with the popular garden aesthetic of the day. Natives good, aliens bad. This xenophobic worldview of garden plants is a mostly new phenomenon in gardening, beginning about the time so many gardeners took up butterfly gardening. I have listened to their arguments, and for one, find them wanting. Sure, there are some garden plants that have escaped into the wild, but the number of bad hombres can be counted on your fingers. The vast majority of garden plants are honest, hard working plants that provide beauty to the space and peace to the spirit.
Mike Dirr, the Georgia based plant guru, calls the European hornbeam “one of the finest landscape trees.” It is well suited for use as a modest growing specimen near patios, as a boulevard planting along streets or in parking lots or even, by means of severe annual pruning, as a tall screen. Its slow rate of growth would not recommend it for shading the house.
My European hornbeam was planted amongst established post oaks in bright shade and has grown steadily over the years, but one would never confuse it with a fast grower. It will grow equally well in full sun, but does not appear to grow any faster in the sun. It tolerates heavy soil, and while typically growing in sites with an acidic pH, it also tolerates slightly alkaline conditions. It seems to tolerate dry conditions somewhat better than our native American hornbeam. It is hardy from zones 5-7.
For more information about horticulture or to see other Plant of the Week columns, visit Extension’s Website, www.uaex.edu, or contact your county extension agent. The Cooperative Extension Service is part of the U of A Division of Agriculture.