|One of many on Brooks|
The Amur corktree, Phellodendron amurense, likely made its first appearance in Ann Arbor at Nichols Arboretum in 1920. Additional plantings were made in subsequent years of that decade, and there may(!) remain several large specimens in the glade at the bottom of the hill. Around town you might run into the occasional mature specimen growing in yards in older residential areas. The City of Ann Arbor also started planting them in modest numbers along the sidewalks starting in the 70's.
|a specimen at Felch/Miner|
|Another Brooks St specimen|
You might confuse a corktree for the more familiar ash. Both groups have stout twigs on which pinnately-compound leaves are arranged in pairs. The cork-tree leaf, however, will emit a turpentine aroma when crushed (the tree is in the citrus family); and the twigs never have a terminal bud.
The fruit, when fresh, looks like a small cherry. Older fruit can be retained for a year, in which case it is hard and dark. Both smell just like the fruit of our local Zanthoxylum (prickly-ash, which is also a citrus relative), and a lot like sumac fruit and the rind of a lime.
The tree's bad reputation comes from its tendency to appear as a volunteer in unwanted places. Matthaei Botanical Gardens director Bob Grese said, "I don't know if I would plant any more of these trees." He said the Arb workers have had to pull out thousands of seedlings. The plant is also shows up in city parks that are being restored as natural areas.
Whereas cork-tree hasn't yet made it onto the list of "Least Wanted" trees in Michigan, it has proven to be a locally noxious pest in the New York City Parks, several Audubon wildlife sanctuaries in eastern Massachusetts and around Philadelphia.
To visit some local corktrees, check the out two largish specimens growing along the driveway entrance to Matthaei Botanical Gardens. In town a very interesting specimen graces the front lawn at 513 Onondaga; and on the west side you can admire a tall specimen at 1937 Ivywood. And let me know if any of these have been removed, if you would. Some city street-side plantings are found at the corner of Fifth St and Pauline (on Fifth), 1111 Miner, 1129 Bydding and along Brooks starting in the 1000 block.