Clay soil can be difficult to plant in. This heavy, water-retaining soil tends to be alkaline and is usually low in nutrients. The majority of trees thrive in nutrient-rich, well-draining soil. Overly wet soil can rot the roots of many trees, especially those with shallow roots. Others, such as the swamp cypress, thrive in wet but loose soil. Still, there are some trees will grow well in heavy clay soil.
Cottonwood trees (Populus sp.) are common across the United States. The characteristics of these trees vary widely depending on the variety, but one thing they all have in common is that they like to have "wet feet," or roots that can handle consistently wet clay. In fact, Cottonwoods are often found growing along streams and riverbanks and grow very well in heavy, wet, alkaline soil.
The Norway maple tree (Acer platanoides) is especially suited to clay soils, according to Beth R. Jarvis, a horticulturist with the University of Minnesota. The tree can grow up to 65 feet tall and features beautiful leaves that change color from maroon in the spring, to bright green in the summer and yellow and orange in the fall. The tree's shallow roots enable it to survive in heavy clay soil, but these same roots can also cause the upheaval of sidewalks, driveways or other pavement.
Norway spruce (Picea abies) is native to Europe and is often called the European spruce. This tree has deeper roots than the Norway maple and is evergreen. The Norway spruce is fast-growing in loose soils, but slower-growing (1 foot per year) in clay soils. This tree can get much larger than the Norway maple--up to 120 feet tall, although such extreme heights are rare--and has very attractive, bluish-green needles.
The American hornbeam (Carpinus caroliniana) is a type of birch tree. This medium-sized tree grows to an average height of 50 feet, with a canopy almost as wide as the tree is tall. The attractive leaves of the tree are slender and oval-shaped. American hornbeam trees are commonly seen growing in the wild in boggy forest areas, along streams and the edges of lakes.