One of three conifers native to Britain and Ireland, Common Juniper is also among the most widely distributed trees in the world. Relatively uncommon and threatened in its native range here, elsewhere it is sometimes considered invasive. Unusually, its juvenile needle-foliage never develops into scale-like foliage.

Its native range is circumpolar across the northern hemisphere, including all of north-west Europe from Iceland to Spain and east across Scandinavia into Russia. In North America it grows from Alaska and British Columbia south to Carolina and Arizona. In Britain and Ireland it grows from sea level to the tree-line, on moorland, heathland, woodland and mountains.

Dioecious. Pollen wind-borne. Seeds dispersed by birds feeding on galbuli (‘berries’). Can live more than 100 years.

Usually small (to 8m), erect, sometimes untidily columnar or bushy, becoming prostrate when exposed or at altitude. Bark grey-brown, shaggy and stringy. Foliage aromatic (‘piney’, citrus), sharp and prickly. Needles in threes, 6-12mm, pointed, with a single white stomatal band on the cupped inner surface. Female cone a fleshy galbulus, 5-10mm, green to purple-black over three years, with three seeds. Dwarf Juniper differs: very prostrate, mucronate needle tips.

Grows on many soils, including very stony ground, but is intolerant of waterlogging and not shade-tolerant. Natural regeneration is preferred for conserving wild populations, but browsing mammals must be excluded. In cultivation many cultivars exist, including prostrate, fastigiate and pendulous forms.

In Scotland’s Caledonian pinewoods it eases the transition from open ground to woodland, sheltering Downy Birch, Rowan and Scots Pine seedlings and Black Grouse (Lyrurus tetrix). On southern British limestone pavements it associates with shade-tolerant plants and ferns. It is the food plant of the scarce Juniper Carpet moth (Thera juniperata), and its ‘berries’ sustain thrushes and other birds.

Considered threatened in Britain and Ireland. Already vulnerable to deer and livestock grazing, it suffers from the pathogen Phytophthora austrocedri, which causes dieback and death; in mainland Europe this is so far confined to nurseries. It is sensitive to wildfire and harmed by moorland burning, and milder winters under climate change may limit germination.

Its timber is rarely available but golden-brown and aromatic, used for small turnery, craft and sometimes smoking food. The female cones are widely used in cooking, especially with game, and most famously as the essential, legally required botanical flavouring of gin. Despite culinary use, it is an abortifacient unsafe in pregnancy; once called ‘bastard killer’, it was used to induce menstruation and can cause miscarriage in livestock.