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6. Amur Cork Tree

Phellodendron amurense: Amur Cork Tree

Cultural Significance

The Amur corktree gained importance in the realm of ancient Chinese government and religion. Its inner bark was used to make a specific yellow dye that discerned religious and bureaucratic documents from less important ones. Recently, analyses of the dyes have allowed scientists and historians to date documents from the ancient period.

A wave of Chinese immigration to the United States in the 1850’s coincided with the need for cheap labor in gold mines and a decade later, on the railroads. Immigrants brought important native flora with them, whether it was for traditional medicinal use or to combat homesickness. The first recorded instance of Amur corktree in the United States was in 1856. Since then, it has been a prized ornamental tree which is still popular on college campuses and as a street tree, especially in New York City.

Native Ecosystems

The Amur corktree is native to Northern China, Korea and Japan and was also cultivated in India for hundreds of years. In China, it is commonly found in the regions of Manchuria, Ussuri and around the Amur River. Amur corktrees can tolerate a wide variety of soil types, withstanding pHs from 5.0 to 8.2. It does best in moist, well-drained soils, but it can stand dryer soils and conditions. It is drought tolerant and does well in areas of high heat and cold.

The Amur corktree is considered invasive in parts of the northeastern United States where it can outcompeting native species such as oaks and hickories. The corktree tends to grow in small clusters that crowd out other species by growing quickly and depriving other species of sunlight. As the corktree displaces oaks and hickories, production of nuts and acorns decreases. The corktree fruit does not offer the same nutritional value as the nuts, as they lack essential fats that animals need to sustain the winter.

Beneficial Uses

The Amur corktree was a natural choice for a city ornamental tree. It has a shallow root system that does not interfere with subterranean structures. It is also tolerant of many air-borne pollutants common in urban environments. Its rot resistant wood has become important for posts used to combat erosion.

The various parts (especially the bark) of the Amur corktree have been instrumental in traditional medicine throughout China, Japan, Korea and India for thousands of years, and continue to be used and studied. Chemical components of the corktree give it strong antimicrobial and antibiotic properties.

Biological Characteristics

The Amur corktree is an important and beautiful tree native to several parts of Asia. Its scientific name is Phellodendron amurense. “Phello” in Greek means “cork” and “dendron” means tree, which yield its common name. Amur is a province in mainland China, which gives the corktree its common name. It belongs to the family Rutaceae, which is commonly known as the Citrus Family. Because of its specific shape, Amur corktree is prized as a shade-bearing tree. Its shelf- like branching gives the tree an extremely wide appearance, but it can reach heights of 50 feet, with a canopy-spread almost equal to its height. The tree is multi-trunked, which also adds to its width and its production of shade.

The Amur corktree has distinctive bark, with a porous appearance and a spongy or corky texture. Below the surface of the bark, the tree has a neon-green layer with important chemical properties. The tree has compound, ovate leaves that produce a variety of scents when crushed. The smells produced from the leaves are varied and have been described as “citrusy,” but likened to disinfectant or even skunk. Amur corktree reaches reproductive maturity from 3-5 years of age. corktree has separate male and female trees (dioecious), with the females producing insignificant flowers which give rise to a sugary fruit known as a “drupe.” The word “drupe” comes from a reference to an “over-ripe olive.” Each small fruit contains five seeds, which may remain viable in the ground for several years.