Large tree with smooth, grey bark. Can reach 30+ m.
Long-stalked, globular male catkins, 2-3 female flowers surrounded by bracts. Flowers not produced every year. Woody, prickly fruit capsules split open to reveal 3-angled slender nuts.
Long, slender, reddish-brown winter buds. Broad-oval leaves with wavy-edges, entire or very blunt-toothed. Delicate young leaves are pale-green, fringed with silky hairs.
Free-draining base-rich to acidic soils. Originally introduced, now naturalised throughout Ireland but is less frequent in west. Self-seeds freely, also widely planted in gardens, hedges.