Black walnut (Juglans nigra) produces a substance called juglone that kills many species of plants and trees, including pine, apple and azalea. With a mature black walnut tree, gardeners must take care to plant only hardy plants and trees in a 50- to 60-foot radius from it, Ohio State University says.
Japanese maples (Acer palmatum) reach 25 feet in both height and width and have bright red leaves in the spring that turn green in summer and orange in autumn. They perform best in dappled sun to light shade and can becomes scorched if given too much sun. Japanese maples are hardy in USDA zones 5 to 8.
Eastern redbud (Cercis canadensis) bears large, heart-shaped, bright green leaves. Its blossoms are deep pink (and occasionally white) rather than red. When the blossoms fall, the trees develop elongated green seed pods. Eastern redbuds can reach 30 feet high and often develop sprawling branches.
The Canadian hemlock (Tsuga canadensis) can reach 80 feet in height in the wild, but averages 25 feet in urban settings. The trees have small cones and tiny dark green needles. This member of the pine family can grow in full sun to full shade but can be picky. Canadian hemlocks do not fare well in poor-draining or sandy soils and are sensitive to drought and heat.
Southern catalpa (Catalpa bignoniodes) is hardy in zones 5 to 9 and tolerant of a wide range of both soil conditions and light. The trees can reach 40 feet high and 25 feet wide. Southern catalpas develop white flowers that are flecked with yellow and purple spots.