Ostrya carpinifolia, the Hop Hornbeam, is a tree in genus Ostrya, in the family Betulaceae, native to Europe.
Ostrya carpinifolia is found in the UK, Italy, France, Austria, Slovenia, Greece, the Balkans, southern Switzerland and Anatolia. It is found in the medium elevations, in southern Italy and Sicily, in the South Apennine mixed montane forests ecoregion of the Mediterranean forests, woodlands, and scrub Biome.
Ostrya carpinifolia is a broadleaf deciduous tree, that can reach up to 24 metres (79 ft). It has a conical or irregular crown and a scaly, rough bark, and alternate and double-toothed birch-like leaves 3–10 cm long.
The flowers are produced in spring, with male catkins 5–10 cm long and female catkins 2–5 cm long. The fruit form in pendulous clusters 3–8 cm long with 6–20 seeds; each seed is a small nut 2–4 mm long, fully enclosed in a bladder-like involucre.
The wood is very heavy and hard. The name Ostrya is derived from the Greek word 'ostrua', "bone-like", referring to this very hard wood. This stable wood was historically used to fashion plane soles.
Ostrya are used as food plants by the larvae of some Lepidoptera species.