Polish Common Juniper – Juniperus communis 'Cracovia' 

Polish Common Juniper – Juniperus communis 'Cracovia' 
Family Cupressaceae – Redwoods, Cypress, Arborvitae, Juniper

Common Juniper is possibly the most widely distributed tree in the world.
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This Polish Common Juniper at the Morton Arboretum is 25 years old. Grows best in full sun.

Common juniper is possibly the most widely distributed tree in the world [1]. It is known variously by over 150 common names, based on naming clones as varieties.  Common juniper is highly valued as an ornamental, provides good ground cover even on stony or sandy sites. This species was first cultivated in 1560. This circumboreal species occurs across North America, Europe, northern Asia and Japan. Common juniper is almost completely circumpolar within the exception of a gap in the Bering Sea region. It is widespread in North America beyond the northern limit of trees, occurring from western Alaska and British Columbia to Newfoundland, Greenland, and Iceland. Common juniper extends southward through New England to the Carolinas and westward through northeastern Illinois, Indiana, northern Ohio, Minnesota, and Nebraska to the western mountains of Washington, California, Arizona, and New Mexico [2].

Common juniper is a native, evergreen shrub or columnar tree. Throughout most of North America, common juniper most often grows as a low, decumbent mat-forming shrub reaching up to 4.9 feet (1.5 m) in height and 7.6 to 13.1 feet (2-4 m) across. In parts of New England common juniper occasionally grows up to 25 feet (7.6 m) in height, and a treelike growth form is reportedly common in Europe. Height at maturity can range from 2 to 50 feet (0.6-15.3 m). At polar limits, common juniper grows as a dwarf shrub in forest tundra.

The bark of common juniper is thin, shreddy or scaly, often exfoliating into thin strips. Twigs tend to be yellowish or green when young but turn brown and harden with age. Leaves are simple, stiff and arranged in whorls of 3. Younger leaves tend to be more needlelike whereas mature leaves are scalelike [2].

Habitat and Plant Communities:
Common juniper is an indicator in a number of forest and shrubland habitat types and community types. It grows as an understory dominant with ponderosa pine, Douglas-fir, lodgepole pine, limber pine, white fir, Engelmann spruce, white spruce, quaking aspen, blue spruce, whitebark pine, subalpine fir, or Rocky Mountain bristlecone pine.

Common associates in northern Utah include common snowberry (Symphoricarpos albus), gooseberry currant (Ribes montigenum), Oregon-grape (Mahonia repens), hairy telegraphplant (Heterotheca villosa), timber milkvetch (Astragalus miser), silvery lupine (Lupinus argenteus), Thurber fescue (Festuca thurberi), elk sedge (Carex geyeri), and bottlebrush squirreltail (Elymus elymoides).

Importance to Wildlife and Livestock:
Wild ungulates generally eat only trace amounts of common juniper. Deer and mountain goats browse common juniper to at least a limited extent in some areas including Wyoming and Montana. Levels of use are typically greatest during the winter or early spring. Common juniper can be important winter mule deer food during some years in parts of the Black Hills. It is also used consistently through the winter months by white-tailed deer in the Swan Valley of Montana . Caribou have been observed feeding on common juniper after fire. Moose feed on common juniper "sparingly" in northern Michigan. It also receives some light summer use by mountain goats in Montana. In northern Canada, barren-ground caribou browse "fairly often" on common juniper where lichen growth is poor. Hares browse common juniper in parts of Ontario where use may range from low to high.

Domestic livestock rarely utilize common juniper. The foliage may be poisonous to domestic goats, although livestock in parts of Europe have reportedly been fed sprays of common juniper with no ill effects. Cones of most junipers are eaten by many species of birds and mammals. Numerous animals, including the American robin and black-capped chickadee, feed on the cones of common juniper whenever they are available. American robins frequently consume large numbers of cones during the spring and fall [2].

The bark of common juniper is thin, shreddy or scaly, often exfoliating into thin strips.

The shade and cover value of common juniper tends to be greatest for birds and small mammals. It provides especially good nesting cover for Merriam's wild turkeys in the Black Hills of South Dakota. In New Jersey, it provides winter roosts for short-eared owls. In the Canadian Northwest Territories, common juniper fans are used in many small mammals' nests [2].
1. USDA, ARS, National Genetic Resources Program. Germplasm Resources Information Network – (GRIN)
2. Tirmenstein, D. 1999. Juniperus communis. In: Fire Effects Information System
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