Winter 2005

Trailing Juniper
Creeper from the North

Those who have visited Illinois Beach State Park near Waukegan likely already have a mental picture of trailing juniper, Juniperus horizontalis. This state-endangered evergreen shrub carpets the low sand dunes there, usually in partnership with its fellow sand-dweller, the bearberry. Rarely rising above six inches, the creeping branches of a single juniper plant sometimes sprawl as far as 60 feet across the dunes.

Naturalists can't help but associate the trailing juniper with the unique landscape of Illinois Beach. This shoreline is one of the last remaining examples of what beaches along the lakefront looked like 200 years ago — and the only place in the region where trailing juniper still grows wild in such abundance.

Admiring the juniper's beautiful silvery-green foliage — its soft, scaly needles and purplish, berry-like cones stark against the sand — it's not hard to understand why the Dream Dictionary says that to see a juniper in a dream signifies "happiness and wealth out of depressed conditions."

Trailing juniper, also known as creeping or horizontal juniper, can't compete against other plants in a typical woods or prairie. Its trick is to thrive on sunny, dry, sandy dunes — too harsh an environment for most plants. According to Ken Klick, an ecologist with the Lake County Forest Preserves, the "amazing collection of plants" that it loosely shares space with — including bearberry, inland New Jersey tea, and western paintbrush — hint at another habitat requirement: a cool climate. "They're northern species from a cooler time in our history," Klick says. "They're only here because Lake Michigan is 100 yards away."

This juniper has been "creeping" south from Milwaukee to Waukegan for the past several thousand years, riding a pulse of sand that followed the natural north-to-south littoral drift along the shoreline.

Trailing juniper prefers more stable dunes, which may explain why botanists don't find it in the comparatively volatile Indiana Dunes. Where wind buries branches with sand, they often die. However, try to lift up a branch, and you'll find that it's anchored. The trailing juniper sends roots down along its branches, so parts that don't get buried may live to form another individual.

Trailing juniper is also easily killed by the prairie fires that occasionally reach it over the sand, though patchy fire can leave some parts alive to grow. Given the poor track record of the seeds in germinating, being lightly burned and partially buried may be important ways for the plant to reproduce and spread. Deer and birds do eat and distribute the juniper's berry-like "false fruits," but these are much more bitter than the fruits of common juniper, the source of the flavoring in gin.

According to Michael Stieber of The Morton Arboretum, cultivated forms of trailing juniper, which resist many air pollutants, are today one of the most popular evergreen groundcovers in gardens and landscapes throughout the U.S. Roughly a century ago, Douglas Nurseries of Waukegan (the city just south of Illinois Beach) earned fame far and wide when they cut and propagated the "Waukegan juniper," a handsome steel-blue variety of trailing juniper found there. Even earlier, in 1804, explorers Lewis and Clark noted that trailing juniper "would make a handsome edging to the borders of a gardin" [sic].

Though trailing juniper lives elsewhere in North America, Illinois' population is quite unique. Beyond earning Waukegan a spot in the horticulturalists' hall of fame, the trailing juniper is an emblem of the classic Chicago Wilderness shoreline.

— Jennifer Tang