The broad canopy of this hop hornbeam arches over the South Walk to display catkins to great effect.
The genus Ostrya is principally a northern temperate family, though there are a few tropical members from Central and South America. It belongs to the birch family, Betulaceae, whose members all have catkins. In the case of Ostrya, the flowers are encased in a bag-like husk, or involucre, which inflates after fertilisation, to produce hop-like clusters, and which gives the plant the common name hop-hornbeam. This species is the most widely grown, and originates from south eastern Europe, Turkey and the Caucasus, where trees are coppiced for firewood. It reaches 20m in height and has a spreading habit, and the bole often develops a distinct fluted, or gnarled habit, and bears cracking, rugged bark. Planted in 1960, this fine specimen has a broad, low canopy; hairy, toothed leaves; and a short, stout, characterful trunk.