A deciduousa shrub or tree which sheds its leaves annually tree in the citrus family (Rutaceae) that reaches heights of 50 feet. Mature specimens have short dark gray trunks with deeply ridged and corky bark, and widely spreading crowns. The leaves are dark green above, much paler below, yellow in the fall, and 11 to 14 inches long. The pinnately compounda leaf which is divided into smaller leaflets, those leaflets arranged on each side of the leaf's central stalk leaves consist of 5-13 slender papery leaflets. Upright cluster of small maroon to yellow-green flowers 2 to 3 inches long, appear in late spring to early summer. Clusters of fleshy, black berries 3/8 inch in diameter remain on the trees into the late fall and winter. Each small berry contains five seeds.
It is adaptable to various environmental conditions in USDA zones 4-7. It is heat-loving, cold and drought tolerant, adaptable to clay to light sand soil types and has no serious pest problems. In areas with ample moisture and good soil, the tree produces large amounts of seed. It can be found in forested areas or along rivers.
History and Introduction
Amur cork tree was introduced to North America from its native China in the 1850s. The extremely hardy, drought-, cold-, and pollution-tolerant species was commonly sold as a street tree, favored for planting in urban areas.
Amur cork tree is a shade tolerant, prolific seed producer capable of adapting to a variety of soil conditions. Due to its quick growing seedlings, young Amur cork trees can germinate and outcompete understory competition, rapidly converting diverse forests and woodlands to monotypic standsan area dominated by a single species. Furthermore, Amur cork tree is known to be allelopathica biological phenomenon by which an organism produces one or more biochemicals that influence the germination, growth, survival, and reproduction of other organisms, inhibiting the germination of seedlings of other plants and potentially modifying the species dynamics of native forest ecosystems in irreversible ways. Amur cork tree gains an advantage over native vegetation in areas with high deer concentrations, as these herbivores do not eat this malodoroussmelling very unpleasant invasive.
Female Amur cork trees are capable of producing thousands of seeds a year once mature. Each drupe contains five seeds which require no stratification prior to germination. Light and fire appear to increase germination rates of Amur cork tree seedlings. Although no studies have been conducted expressly on the longevity of Amur cork tree seeds in the seedbank, the species has a moderately hard endocarp, suggesting seeds may persist as viable propagules for at least several years. Vectors include birds and water.
For mature trees Amur cork trees can resprout from roots, so simply cutting down a mature tree will not eliminate the plant or prevent its growth and spread. For very large trees, cutting or girdling the tree followed by painting with a triclopyr-based systemic herbicide can be an effective strategy for removal. Focus on reducing or stopping fruit production and spread.
The most effective and easiest solution is the “hack and squirt” method. This involves making a chop into the bark with a hatchet in a downward motion then squirting in herbicide. Calling a professional arborist is also an option as they have access to injection herbicides that can be very effective.
Cork Tree Leaves
Amur Cork Tree, Sakhalin Cork Tree, shikerebe-ni (Ainu), hwangbyeok (Korea), kihada (Japan)
Eastern Asia—Northern China, Manchuria, Korea, Ussuri Region, Amur Region, Japan
Common Prickly-Ash (Zanthoxylum americanum)
Cork Tree Bark
Cork Tree Fruit
Image Attributions: Cork Tree Leaves - Jean-Pol Grandmont, Wikimedia Commons | Cork Tree - Jean-Pol Grandmont, Wikimedia Commons | Cork Tree Bark - Bostonian13, Wikimedia Commons | Cork Tree Fruit - James M, Flickr