top of page
Carpinus japonica
Blume
Japanese Hornbeam
Betulaceae
Carpinus japonica is a deciduous tree species in the family Betulaceae. It is endemic to the mountains of Japan, but is sometimes cultivated as an ornamental.
Description
Carpinus japonica is a deciduous tree. Leaves are alternate, simple, narrowly ovate to oblong, 6 to 10 cm long and 2.5 to 4 cm wide, with a rounded base and a long, tapering tip. The margins are doubly serrated with sharply pointed teeth, and the surface has obvious lateral veins; there are 20 to 24 pairs of lateral veins per leaf. Leaves are dark green above, with some brownish hairs on the nerves beneath; fall color is absent. The petiole is rather short, 8 to 15 mm long, and also hairy. The bark is grayish brown, developing scaly ridges. As with other species in the family, Carpinus japonica has separate male and female flower clusters (called catkins or aments) on a tree. Male catkins grow up to 5 cm long, and have conspicuous narrowly ovate scales that are about 6 mm long. Female catkins eventually mature to become fruiting clusters 7 cm long. They consist of a 4 mm long seed (technically a nutlet) surrounded by a papery bract. Bracts are 15 to 22 mm long, narrowly ovate, with coarse teeth (Johnson 2022; Ohwi et al. 1965).
Carpinus japonica is one of a few species within the section Distegocarpus of genus Carpinus that are distinguished by leaves with many parallel veins, scaly bark, and dense clusters of fruit reminiscent of hops (Johnson 2022). They are intermediate in morphology between hophornbeams (Ostrya) and the rest of the hornbeams (Carpinus sect. Carpinus), and possibly represent the products of an ancient hybridization event between them (Wang et al. 2022). It is most similar to the heartleaf hornbeam (Carpinus cordata) which is also found in Japan, but that species has wider leaves (4 to 7 cm wide) with fewer (15 to 20) pairs of lateral veins and a more heart-shaped base (Ohwi et al. 1965).
Carpinus japonica is one of a few species within the section Distegocarpus of genus Carpinus that are distinguished by leaves with many parallel veins, scaly bark, and dense clusters of fruit reminiscent of hops (Johnson 2022). They are intermediate in morphology between hophornbeams (Ostrya) and the rest of the hornbeams (Carpinus sect. Carpinus), and possibly represent the products of an ancient hybridization event between them (Wang et al. 2022). It is most similar to the heartleaf hornbeam (Carpinus cordata) which is also found in Japan, but that species has wider leaves (4 to 7 cm wide) with fewer (15 to 20) pairs of lateral veins and a more heart-shaped base (Ohwi et al. 1965).
Uses
Note: Please see the disclaimer regarding any information about medical or edible uses.
Carpinus japonica is sometimes cultivated for ornament, and a few cultivars are available (Johnson 2022). It grows in USDA zones 5 to 7 (Sibley 2009).
Distribution
Carpinus japonica is found in forests, high-elevation valleys; it is shade-intolerant, so it needs disturbances for seedlings to establish. It is endemic to Japan, and is found in Honshu, Shikoku, and Kyushu (Shaw et al. 2014).
Status
Carpinus japonica is listed on the IUCN Red List as “Data Deficient”. Although it is reportedly rare, there is currently a lack of data to determine whether it is threatened or not (Shaw et al. 2014).
References
Johnson, O. 2022. Carpinus japonica Blume. Trees and Shrubs Online. [accessed 2022 Aug 23]. https://treesandshrubsonline.org/articles/carpinus/carpinus-japonica/.
Ohwi, J., Meyer, F. G., and Walker E, H. 1965. Flora of Japan. Washington, D.C.: Smithsonian Institution.
Shaw, K., Roy, S., and Wilson, B. 2014. Carpinus japonica. The IUCN Red List of Threatened Species https://dx.doi.org/10.2305/IUCN.UK.2014-3.RLTS.T194662A2356594.en.
Sibley, D. A. 2009. The Sibley Guide to Trees. New York: Alfred A. Knopf.
Wang, Z., Kang, M., Li, J., Zhang, Z., Wang, Y., Chen, C., Yang, Y., and Liu, J. 2022. Genomic evidence for homoploid hybrid speciation between ancestors of two different genera. Nature Communications, 13: 1987.
Ohwi, J., Meyer, F. G., and Walker E, H. 1965. Flora of Japan. Washington, D.C.: Smithsonian Institution.
Shaw, K., Roy, S., and Wilson, B. 2014. Carpinus japonica. The IUCN Red List of Threatened Species https://dx.doi.org/10.2305/IUCN.UK.2014-3.RLTS.T194662A2356594.en.
Sibley, D. A. 2009. The Sibley Guide to Trees. New York: Alfred A. Knopf.
Wang, Z., Kang, M., Li, J., Zhang, Z., Wang, Y., Chen, C., Yang, Y., and Liu, J. 2022. Genomic evidence for homoploid hybrid speciation between ancestors of two different genera. Nature Communications, 13: 1987.
Description
bottom of page