A very slow-growing tree whose timber is always denser than water, so it sinks. More often seen tightly clipped as hedging and topiary, but in a few places it forms wild, dark, atmospheric thickets.

Native to north-western Europe except Ireland and Scandinavia, also North Africa, the Balkans, Caucasus and Iran. Considered native (though contentiously) to Britain, restricted in natural stands to a few southern English locations that lent their names to places such as Box Hill, Surrey, and Boxgrove, Sussex. It is widely cultivated in British and Irish gardens.

Monoecious, producing inconspicuous yellow flowers without petals in early spring, insect-pollinated. Fruit a three-sided capsule containing 3–6 seeds, dispersed by ants (myrmecochory), which are attracted to nutrients attached to part of the seed (the elaiosome).

Small (8-10m), usually spreading and wider than tall except in the rare woodland form, where multiple winding stems reach for light. Bark pale brown, finely cracked and corky. Twigs minutely hairy, squarish and slightly winged when young. The foliage smells pungently of cat urine, especially in warmth. Leaves evergreen (2-3cm), opposite, oval, glossy dark green above, paler below, notch-tipped, on a very short hairy petiole. Flowers pale green with yellow anthers in April. Seed capsule small (under 1cm), three-sided with six ridges, green ripening brown and splitting to release seeds.

Highly shade-tolerant, growing in the understorey with European Beech and European Yew, forming thickets that exclude ground flora. Pure thickets are rare, mostly on steep, loose, chalky or limestone slopes that few other species can hold. Stems grow slowly, taking at least 200 years to reach marketable size, so the species is far more common in cultivation, long used to give structure to formal gardens and to be tightly clipped into intricate topiary.

Provides winter shelter to wildlife on otherwise challenging soils. A unique relationship with ants, especially red ants (Myrmica). Its early spring flowers provide a valuable source of nectar and pollen.

Resistant to honey fungus, but seriously threatened by two pests. Box-tree Moth (Cydalima perspectalis), an Asian species first recorded in Europe in 2006 and reaching England in 2008, has larvae that can completely defoliate plants between July and September; small plants can be hand-stripped, larger ones treated with nematode biocontrol. Box blight (Calonectria spp.) particularly affects densely clipped hedges and topiary, causing dieback and disfigurement, often fatal unless cut back hard.

Its fine-grained, creamy-white, almost bone-like timber is very dense, with up to six growth rings per millimetre. Rarely available over 20cm in diameter, it is used for engraving such as woodblock printing, turning (including chess pieces), tool handles and wooden musical instruments, including early bassoons and clarinets.