Trees of the Arboretum

The fringetree is a small deciduous tree that is native to the eastern United States. It prefers full to part sun, and reaches a mature height and spread of 12 to 20 feet. It has separate male and female trees. Both the male and the female trees produce showy white flowers in the spring. In the summer, the fruits provide food for a variety of birds and other animals. The fringetree has relatively low disease susceptibility, but may be attacked by emerald ash borer.

Black Gum is also called black tupelo. It reaches a mature height of 30 to 50 feet and a mature spread of 20 to 30 feet. It has a slow to medium growth rate and likes full to partial sun. It can grow in a variety of soil types, including acidic, loamy, moist, rich, sandy, silty loam, and well-drained. Black gum has stunning fall colors, with leaf colors ranging from yellow and orange to red and purple. It has a small bluish-black fruit that ripens in late September and early October, providing food for birds and mammals.

Cherry (Prunus serrulate) This tree produces beautiful, deep pink double blossoms in spring, and yellow, orange, or bronze-colored leaves in the fall. Its lifespan is 15 to 25 years. It likes full sun and can grow in a variety of soil types, including acidic, alkaline, clay, drought, loamy, sandy, well-drained, or wet. It reaches a mature height of 30 to 40 feet and mature spread of 30 to 40 feet. This is a non-fruit bearing cherry tree. As a strictly decorative tree, it has low value to wildlife, and is sensitive to pollution.

Dogwood blooms in April to May and has fruit that is eaten by many types of birds, chipmunks, squirrels, skunks, rabbits, deer. It grows in full sun or partial sun. At maturity it reaches a height of 20 to 25 feet. Dogwoods grow in a variety of soils, including acidic, clay, loamy, moist, rich, or well-drained, and are popular landscaping trees.

The American hornbeam is a medium-sized tree in the beech family, and is native to eastern North America. It likes partial to deep shade, and is considered to be an understory tree in a forest. It reaches a mature height of 20 to 30 feet and a mature spread of 20 to 35 feet. The hornbeam is difficult to transplant and is sensitive to drought, heat, and soil compaction, though it is resistant to damage by deer.
The hornbeam is a larval host for some species of swallowtail butterflies, and the seeds and buds are a food source for birds, squirrels, foxes. Hornbeams are resistant to black walnut(*), and can also stand up against wind.

Red maple mature height: 40-60 feet; and it needs full or partial sun.

 There are several varieties of oak. We describe the white oak (Quercus alba) here. It reaches a mature height of 50 to 80 feet, and a mature spread of 50 to 80 feet. Its growth rate is slow to medium. Oaks grow well in full sun or partial sun and are drought tolerant. They can grow in acidic, drought, moist, and well-drained soil. Acorns are an excellent source of food for a variety of wildlife.

The quaking aspen is fast growing and reaches a mature height of 40 to 50 feet and a mature spread of 20 to 30 feet. In the fall the leaves are bright yellow. It likes full sun and can grow in acidic, clay, loamy, moist, sandy, or well-drained soil. Of all the trees in North America, the quaking aspen has the widest natural range. Once planted, the tree sends up sprouts from its roots. These clones will remain interconnected, meaning that a grove of quaking aspen are probably all clones of each other.
The leaves are eaten by snowshoe hare, deer and elk. In the right location, quaking aspens provide building materials for beavers. The buds provide food in the winter for some birds, such as grouse.
Quaking aspen are among the first trees to repopulation a forest following a forest fire, and are also used to repopulate forests that have been over-harvested.

This tree has an abundance of pink flowers in April. It prefers full sun or partial sun/shade, and can grow in a variety of soil types including acidic, alkaline, loamy, clay, moist, rich, or sandy. It prefers to be in well-drained soil. It will reach a mature height of 20 to 30 feet, and a mature spread of 25 to 35 feet. It is native to North American, though there are also varieties of redbud trees in Europe and Asia.

The red cedar is an evergreen tree and grows best in full sunlight and open spaces. It has a medium growth rate and reaches 40 to 50 feet at maturity, with a spread of 8 to 20 feet. It can tolerate a variety of soils, including acidic, alkaline, clay, loamy, moist, rich, sandy, silty loam, and well-drained. The fruit is a favorite of cedar waxwings. The foliage provides nesting for sparrows, robins, warblers, and mockingbirds.

In Pennsylvania, the serviceberry blooms in April, with delicate white flowers. In the fall the leaves turn shades of red and gold. At maturity, the tree has a height and spread of 15 to 25 feet. It grows well in both full and partial sun, and prefers acidic, moist, well-drained soil. The red berries are eaten by birds in the summer, but are also used to make pies and preserves.

The slippery elm is found in the eastern and central United States. It reaches a mature height of 60 feet and a mature spread of 50 feet. It prefers moist, rich, deep soil, with variable pH, but can also be found growing in dryer soils. The slippery elm is similar to the American elm in many ways, including being susceptible to Dutch elm disease, though it is not affected as severely. It is called “slippery” elm because of the mucilaginous layer under the bark. Native Americans and pioneers used to chew on the inner bark to quench thirst, when water was not readily available.
Birds and small animals eat the seeds, while deer and rabbits will eat the twigs. The wood can be used commercially for furniture, though it is considered to be inferior the American elm.

This is another flowering tree, though it usually blooms in May or June, well past the danger of frost damage to the blossoms. It will reach a height of 10 to 20 feet and a spread of 10 to 20 feet. It has a medium to fast rate of growth. Magnolias prefer full sun but are also fine in partial sun, and they can grow in a variety of soils, including acidic, loamy, moist rich, sandy, silty loam, well-drained, or wet. In the fall its red fruit feeds various birds, including towhees, blue jays, quail, and turkeys, as well as squirrels, mice.

The Sweet Gum tree needs plenty of space for root development. It has a mature height of 60-70 feet and a mature spread: 40-50 feet. It can grow in a variety of soils, including acidic, clay, loamy, moist, sandy, well-drained, and wet. It likes full sun and has glossy green leaves that turn yellow, orange, red, and purple in fall. The seeds are eaten by a variety of birds, chipmunks, squirrels.

Sycamores can grow to a mature height of 75 to 90 feet, with a trunk diameter as large as 10 feet. The tree prefers full sun, and while it prefers moist, fertile soil, can accommodate clay, sand, loam, alkaline, and wet soils. It is pollution tolerant and moderately drought tolerant, but is prone to pest and disease problems.

White pines grow to a mature height of 50 to 80 feet, with a spread of 20 to 40 feet. They are fast growing, with a height increase of around 24 inches per year and like full sun or part shade. They are easy to transplants but are sensitive to road salt, air pollution, and soil compaction. White pines provide a nesting site for a variety of birds. Several animals eat the seeds, including black bears, rabbits, squirrels, and many types of birds.

Acidic—a substance with a pH* less than 7. The lower the pH, the higher the concentration of hydrogen ions (H⁺). Correspondingly, there is a lower concentration of hydroxyls (OH^–).

Alkaline—a substance with a pH* higher than 7. The higher the pH, the lower the concentration of hydrogen ions. Correspondingly, there is a higher concentration of hydroxyls (OH^–)

Black walnut trees— produce a toxin called juglone that acts as an herbicide and can kill competing plants. It is an evolutionary protection within an environment, to keep from being out-competed for space. There are some plants and trees that have co-evolved with the black walnut, and are not affected by the toxin.

Clay soil—dense, tightly packed soil formed primarily from mineral particles, which means it has little to no organic material, though it can hold calcium, potassium, and magnesium, which are needed for plant growth. Clay holds water well, but can become waterlogged. Clay is sticky.

Deciduous tree—a tree that loses its leaves in the fall and grows new leaves in the spring. The word deciduous means “to fall off.”

Delta**—a flat land formation, often in the shape of a triangle, that is formed by the buildup of sediment, specifically silt*. Deltas often form where a river meets a slower moving body of water. It is common to find deltas where the mouth of a river empties into a lake or ocean.

Loam/loamy—soil that contains sand, silt,* and clay,* preferably in equal parts. Loamy soil is considered to be the ideal soil for gardens because it holds water and contains nutrients needed by most plants.

Mucilaginous—mucus-like

pH—“potential of hydrogen.” pH is a measure of the concentration of hydrogen ions (H⁺) in a substance. The higher the concentration of hydrogen ion, the lower the pH. The lower the concentration, the higher the pH. The pH scale goes from 0 to 14. Distilled water, which has a pH of 7, has an equal concentration of hydrogen ions (H⁺) and hydroxyls (OH^–)

Silt—granular soil in which the granular particles are larger than clay* and smaller than sand. It is made up primarily of worn down quartz and feldspar. When dry, it feels like flour, when wet it forms what we typically refer to as mud. Silt can be carried by glaciers and rivers, and can settle in deposits that, over time, can build up new land, such as deltas*.

Silty loam—Descriptions vary, but silty loam has about 50 to 85% silt, 0 to 25% clay, and 0 to 50% sand. This differs from loam, which has approximately equal amounts of silt, clay, and sand.

Spread—This is a measure of how wide the tree branches are, measured at the widest point of the tree. The measurement is taken starting on one side, and going straight through where the trunk would be, if it extended up that far, to the other side of the tree.

Understory trees—trees that grow under the forest’s main canopy. These can be trees that are stunted in growth because of lack of adequate light, or trees that have low light requirements.

(*) An asterisk next to a word means that it is defined somewhere in the glossary.
(**) A double asterisk means that the word was used in the glossary and is defined, but does not relate specifically to the arboretum.