Buckthorn is an invasive, noxious shrub or small tree once used as a medicinal plant. This plant family consists of 150 species and is native to North Africa, Europe and North Asia. Until the 1800s, it was used by physicians as a purgative until its actions were considered too severe. It’s regarded as an invasive plant because it lacks bio-controls in the environment, forms a dense, impenetrable layer of vegetation and becomes a host for crown nest fungus and soybean aphid. http://www.invasivespeciesinfo.gov
Accounts of the buckthorn appear in Anglo-Saxon writings, and it’s mentioned in glossaries before the Norman Conquest of England in 1066. Welsh physicians boiled its fruit with honey and prescribed it as a laxative drink. Physicians stopped using this drink when tests proved it to be dangerous. Some people believe that Jesus Christ’s Crown of Thorns was made of buckthorn.
Buckthorn, also highway thorn or waythorn, belongs to the family RHAMNACEAE and the order Rhamnales. It grows to twelve feet in temperate and tropical zones. It has smooth, blackish-brown bark and an erect stem. The twigs on smaller branches are ash-colored and end with a sharp thorn. The oval, saw-toothed leaves grow in small bunches, and at the plant’s base young shoots appear. Young leaves have soft fuzz. Small, greenish-yellow flowers with four petals are produced by the plant. Its fruit is orbed, tiny berries in clusters that are black when ripe and otherwise brown.
Chicago gardeners should remove most buckthorns from their gardens because they are a threat to forest preserves, nature centers and natural areas in and around the city. They upset Chicago’s ecosystem and vie with native plants for nutrients, space and sunlight. Buckthorns on the invasive list include European, common and glossy buckthorn. Also, Dahurian, Japanese and Chinese buckthorn are considered invasive plants. http://www.illinoiswildflowers.info/wetland/plants/eur_milfoil.html