Corylus

A rounded, multi-stemmed deciduous shrub native across eastern and central North America, grown for its edible nuts and its season-opening catkins. Showy 2-3 inch yellowish-brown male catkins dangle from bare branches in early spring before the ovate, double-toothed leaves emerge; small egg-shaped edible nuts ripen inside leafy husks by mid- to late summer. Easygoing in average soil and tolerant of clay and black walnut, it suckers into thickets that screen and shelter wildlife.

Filbert (Corylus maxima) is a large deciduous shrub native to southeastern Europe and southwestern Asia, from the Balkans through to Ordu in Turkey, where it has been cultivated for its larger-than-hazelnut edible fruits for millennia. In the garden it doubles as bold structural foliage — especially the wine-purple cultivar 'Purpurea' — making it as much an ornamental as a productive shrub. The honest catch is its sheer bulk and suckering ambition: left unmanaged it rapidly forms an impenetrable multi-stemmed thicket 6–10 m tall, requires another Corylus nearby for worthwhile nut crops, and squirrels reliably harvest the nuts before the gardener does.