The Common Juniper (Juniperus communis) is a shrub or small tree, very variable and often a low spreading shrub, but occasionally reaching 10 m tall. 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.
Common Juniper - foliage and cones
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 separate male and female plants. 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.
As to be expected from the wide range, it is very variable, with several infraspecific taxa:
- Juniperus communis subsp. communis - Common Juniper. Usually an erect shrub or small tree, with leaves 8-20 mm long; found at low to moderate altitude in temperate climates.
- Juniperus communis subsp. communis var. communis - Europe, most of northern Asia
- Juniperus communis subsp. communis var. depressa - North America
- Juniperus communis subsp. communis var. nipponica - Japan (status uncertain, often treated as J. rigida var. nipponica)
- Juniperus communis subsp. alpina - Alpine Juniper. Usually a prostrate ground-hugging shrub, with leaves 3-8 mm long; found in subarctic areas and high altitude alpine zones in temperate areas.
- Juniperus communis subsp. alpina var. alpina - Greenland, Europe & Asia
- Juniperus communis subsp. alpina var. megistocarpa - Eastern Canada (doubtfully distinct from var. alpina)
- Juniperus communis subsp. alpina var. jackii - Western North America
Some botanists treat subsp. alpina at the lower rank of variety, in which case the correct name is Juniperus communis var. saxatilis, though the name Juniperus communis var. montana is also seen.
It is commonly used in horticulture as an ornamental shrub, but is too small to have any general wood usage. In Scandinavia, however, juniper wood is used for making containers for storing small quantities of dairy products such as butter and cheese, and also for making wooden butter knives. Its astringent blue-black seed cones, commonly known as juniper berries, are too bitter to eat raw and are usually sold dried and used to flavor meats, sauces, and stuffings. They are generally crushed before use to release their flavour. The cones are used to flavour gin. In fact, the name is derived from the French word for juniper berry, geni vre, which is the name for gin in France. Since juniper berries have a strong taste, they should be used sparingly. They are generally used to enhance meat with a strong flavour, such as game, including game birds, or tongue.
- Arboretum de Villardebelle photos of cones & shoots (http://www.pinetum.org/cones/JUcones.htm)