Explore the Grounds

North American Collections

Tour the most botanically diverse regions of the United States when you visit the North American Collections at The Morton Arboretum.

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Tour the most botanically diverse regions of the United States when you visit the North American Collections at The Morton Arboretum. Your day trip to Appalachia, Eastern United States Wetlands, and the woods of the Midwest will introduce you to the important plants of these habitats.

Covering almost 5% of the Earth’s surface, North America has a vast temperate area, varied topography, and a range of climates that support plant life that is as exciting and beautiful as any in the world.

Through years of collecting and working with plants from the eastern, southeastern, western, and midwestern North America, Arboretum horticulturists have identified representative species that also perform well in northern Illinois’ climate and soil conditions. Enhancing the collections is an ongoing project; recent trips resulted in important additions to the collections.

Beyond highlighting the beauty of these plants and their environments, the collections conserve North American native plants and educate guests about native species.

Along the cool slopes of the Appalachia Collection at The Morton Arboretum, you can see plants rarely found outside the lush microcosms of their native habitats.

East Side, Parking Lot 16

The Appalachian Mountains are a series of ancient ranges running north and south along 1,500 miles of eastern North America, from Newfoundland to Georgia. They feature seemingly infinite ridges and valleys with moist, mild climates that support a rich variety of plants, including several endemic species, plants that occur only on these mountains.

The majority of plants in the Arboretum’s Appalachia Collection are from the central and southern sections of the mountains, where species diversity is richest. The collection is anchored by oaks that thrive on a north-facing slope protected from direct sun, dry winds, and extreme temperature fluctuations. Other trees and shrubs include groves of Eastern hemlock (Tsuga canadensis) and the Arboretum’s largest stand of pawpaws (Asimina triloba). Pawpaw trees produce the largest edible fruit native to North America, also called pawpaws, which are prized for their sweet, custardlike pulp.

In spring, stop to admire the riot of colorful wildflowers, as well as nonflowering plants such as the perennial American umbrella-leaf (Diphylleia cymosa).

Collecting trips to the southeastern United States continue to expand the delightful Appalachia Collection.

Walk the trails through the Eastern United States Wetlands Collection at The Morton Arboretum to see how a variety of plants have adapted to living in a sometimes wet, sometimes dry environment.

Parking Lot 18, off Main Trail Loop 1

Wetlands include floodplains, which are low, flat areas that flood periodically but are not continually underwater. More than 360 plants native to the eastern United States wetland habitats have been assembled on three acres next to the DuPage River, on the East Side of the Arboretum. They thrive in the seasonal floods that inundate this natural floodplain habitat. When the river overflows its banks, it deposits organic matter and minerals that replenish the deep, rich soil in which these plants grow.

Wetlands play an important role in both natural and built landscapes. They protect adjacent dry areas by absorbing floodwaters, and they filter land-based pollutants and other runoff that would contaminate rivers and streams.

This collection, started in 1925, today includes such impressive specimens as the large Eastern white pine (Pinus strobus) and the Eastern arborvitae (Thuja occidentalis), located along the service road. Autumn is an especially good time to visit to see the ripening fruit of the Southern arrowhead (Viburnum dentatum), the vibrant red fall foliage of black tupelo (Nyssa sylvatica), and the Florida corkwood (Leitneria floridana), a shrub that grows in colonies of tall, slender stalks that keep their leathery leaves late into the season. Don’t miss the mysterious “knees” of the bald cypress (Taxodium distichum). The function of the conical woody outgrowths from the roots is unknown, but they may help stabilize the trees in soft, muddy wetland soil.

You may be surprised by the diversity of native plants represented in the Midwest United States Collection, which highlights the trees and other plants native to the northern half of Illinois as well as Wisconsin, Minnesota, Michigan, Ohio, Indiana, Iowa, and Missouri. You can challenge yourself to find all 13 species of oaks. 

East Side, Parking Lot 2, Main Trail Loop 1, and Parking Lot 3, Northern Illinois Trail

Northern, southern, eastern and western bioregions meet in the Midwest, creating a transitional area characterized by a mix of prairie, savanna, and woodlands. Over the years, however, much of the region has been converted into farmland and urban areas. As a result, remaining natural areas have become extremely fragmented. Parts of the Arboretum’s Midwest Collection include well-preserved woods, with some trees dating before 19th-century settlement,  that reveal the historic diversity of the native plants of this region. 

Wild-derived plants make up 93% of the collection. Among the 171 kinds of plants here is a federally threatened species, lakeside daisy (Tetraneuris herbacea). Another rare plant in this collection is the Illinois-endangered bearberry (Arctostaphylos uva-ursi var. coactilis), which grows in the sandy soils surrounding Lake Michigan. The red pines (Pinus resinosa) were collected from an endangered population in Illinois. 

Among the outstanding assemblage of oaks, look for the pin oak (Quercus palustris), a large tree in the rear of the collection whose limbs reach the ground like a skirt. For great fall colors, check out the scarlet and purple foliage of the black tupelo or black gum (Nyssa sylvatica). You might even see wildlife feeding on its black-blue fruit. Kentucky viburnum or arrowwood (Viburnum molle) also has good fall color and attractive flaky bark that stands out all year. 

The Midwest United States Collection is The Morton Arboretum’s youngest geographic collection, begun in 1999. It serves as a resource for classes and individuals interested in learning about native trees and shrubs and highlights regional native trees and shrubs suitable for the home landscape.


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