Juniperus communis, the Common Juniper, is a species in the genus Juniperus, in the family Cupressaceae. It has the largest range of any woody plant, throughout the cool temperate Northern Hemisphere from the Arctic south in mountains to around 30°N latitude in North America, Europe and Asia.
Juniperus communis is a shrub or small tree, very variable and often a low spreading shrub, but occasionally reaching 10 m tall. Common Juniper has needle-like leaves in whorls of three; the leaves are green, with a single white stomatal band on the inner surface. It is dioecious, with male and female cones on separate plants, which are wind pollinated.
The seed cones are berry-like, green ripening in 18 months to purple-black with a blue waxy coating; they are spherical, 4–12 mm diameter, and usually have three (occasionally six) fused scales, each scale with a single seed. The seeds are dispersed when birds eat the cones, digesting the fleshy scales and passing the hard seeds in their droppings. The male cones are yellow, 2–3 mm long, and fall soon after shedding their pollen in March–April.
Juniper berries have long been used as medicine by many cultures. Juniper berries act as a strong urinary tract disinfectant if consumed, and were used by Native Americans as an herbal remedy for diabetes. Western American tribes combined the berries of Juniperus communis with Berberis root bark in a herbal tea. Native Americans also used juniper berries as a female contraceptive.