1299 Carpinus japonicaCommon Names: Japanese hornbeam Family: Betulaceae (birch Family)
Japanese hornbeam is a smallish tree, to around 50 ft (15 m) in height in its native Japan, but often less than 30 ft (9 m) tall in cultivation. This is a handsome tree with layered, wide spreading branches and (with age) fissured bark with scaly flakes. The deciduous leaves are oblong, 2-4 in (5-10 cm) in length, downy top and bottom, and with alternating small and larger teeth along the margins. The 20-24 pairs of parallel, recessed veins cause the leaf to appear pleated. In autumn, the leaves sometimes turn a dull reddish brown. Male and female flowers are borne in separate catkins on the same tree. The catkins start out erect and are clothed by overlapping scale-like bracts. The flowers are wind pollinated. After pollination, the catkins become pendulous and look a lot like those of hops. Mature catkins are a couple inches (5 cm) long and contain a hard, ribbed nutlet under each bract.
Japanese hornbeam is similar to American hornbeam (C. caroliniana), but the latter has only 10-14 pairs of leaf veins, smooth, sinewy bark, and larger catkins. Compare Japanese hornbeam also to European hornbeam (C. betulus), which is a larger tree; has fewer leaf veins; and has a very different looking fruiting catkin characterized by leaf-like bracts that have three elongate lobes.
Carpinus japonica (Japanese hornbeam) is native to Japan where it grows in the forest understory.
Light: Japanese hornbeam is tolerant of full sun to nearly full shade. It probably does best in partial shade throughout most of its useful range, but should get full sun in zone 4 and full shade in zone 8. Moisture: A moist but well drained soils suits this handsome little tree just fine. Japanese hornbeam thrives on neutral to limey soils and, once established, should not need supplemental watering. Hardiness: USDA Zones 4 - 8 . Propagation: Sow ripe seed in autumn and expect germination the following spring. Seed that has become hardened and dry must be pre-stratified under warm, then cool conditions before it will lose dormancy.
This is a low maintenance little tree, ideal for shady areas under big pines or oaks. Japanese hornbeam is among the most useful small specimen trees owing to its slow growth rate and small ultimate size; attractive floral catkins in spring; deeply veined leaves with a pleated appearance in summer; ornamental fruiting clusters in fall; and graceful, layered habit, best appreciated in its winter nakedness. You can use this little subcanopy tree for naturalizing in a woodland setting, or as a stand alone specimen in a small landscape or patio. Japanese hornbeam’s small maximum size makes it a practical street tree, as well.
The genus Carpinus consists of some 35 species of smallish trees and shrubs occurring mainly in eastern Asia with one species in North America, one species in Central America, and two in Europe. All make beautiful specimen trees and at least 18 species can be found in cultivation.
Steve Christman 10/15/17