Rutaceae (citruses or rues)
Amur corktree is a medium-sized tree with a broad-spreading, rounded crown and dark green foliage.
Leaves are opposite, pinnately compound, up to 14 inches long, with 5–11 leaflets that are 4½ inches long, elliptical, with an acute tip; upper surface dark green, lower surface lighter. When bruised, leaves smell something like turpentine.
Bark, with age, becomes uniquely ridged and corky.
Flowers May–June; in erect clusters of small yellow or yellowish-green flowers, male and female flowers on separate plants.
Fruits clusters of pea-sized fleshy, round berries, green but maturing to black in October, containing 5 seeds each, persisting into winter.
Other Common Names
Height: 30 to 45 feet.
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Habitat and Conservation
This hardy species adapts to a wide variety of soil types, withstands heat and drought, tolerates cold, and resists pests. These characteristics make it attractive for landscaping, but please do not plant it. The qualities that make it survive well also contribute to its invasive nature. The female trees, especially, can be highly invasive.
Considered invasive in many states, but not yet in Missouri. It is basically free of pests and adapts to many soil conditions as well as pollution and drought. The male and female trees are easily distinguished in the fall, when female trees have clusters of black berries. Old trees with massive branches and attractive bark develop a sculptured look. It is a poor choice as a street tree, because of its spreading, low-branching habit.
In addition to its use as a shade and landscape tree in America, this plant has a long history in traditional Chinese medicine. It has proven itself invasive in the northeastern United States and in Illinois, and has shown invasive tendencies in St. Louis.
It's a bad deal for nature if this plant starts displacing our native trees. Oaks and hickories, for example, provide important, nutritious nuts that help wildlife survive winter, but Amur corktree provides berries sweet with sugar but with far less nutritional value. As corktrees increase, wildlife will decrease.
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About Trees, Shrubs and Woody Vines in Missouri
There are no sharp dividing lines between trees, shrubs, and woody vines, or even between woody and nonwoody plants. “Wood” is a type of tissue made of cellulose and lignin that many plants develop as they mature — whether they are “woody” or not. Trees are woody plants over 13 feet tall with a single trunk. Shrubs are less than 13 feet tall, with multiple stems. Vines require support or else sprawl over the ground.