July 5, 2010
Contact: Marc Imlay, Mid-Atlantic Exotic Pest Plant Council, Maryland Native Plant Society
It is not Holly
ANNAPOLIS, MD (July 5, 2010) - Mahonia bealei is commonly known as leatherleaf mahonia or leatherleaf holly. Leatherleaf mahonia has been classified as highly invasive in southern states by the USDA and University of Georgia. So far investigation reveals that Mahonia bealei is a very serious invasive in Maryland only in Swann Park, Charles County, in Southern Maryland. It shows up occasionally elsewhere in Maryland, D.C. and Virginia. It was found twice in the middle of the 150 acre Little Paint Branch Park far from any landscaping. In the 200 acre Swann Park about a dozen seedlings have been found far from any landscaping over an area about 500 feet x 2,000 feet. Due to its invasive qualities and its strengthening foothold in Maryland, the Maryland Invasive Species Council has chosen leatherleaf mahonia to be the July Invader of the Month.
Leatherleaf mahonia is an evergreen shrub which can grow from 5 – 10 feet tall. For the casual observer, leatherleaf mahonia is most easily recognized by its leathery spiny leaves which look like giant holly leaves. Flowing occurs in late winter when fragrant lemon-yellow flowers develop. The fruits are green berries that turn bluish-black with a waxy type coating. The berries hang in grapelike clusters.
Leatherleaf mahonia does best in shady well drained areas. In states where it is better established it appears more commonly in bottomland forests. It has been sighted in Florida, Alabama, and South Carolina, Virginia, Maryland and DC. Because of its invasive nature leatherleaf mahonia has been removed from the Prince George’s County Landscape Manual in Maryland.
As is the case with many invasive species, leatherleaf mahonia was introduced intentionally with the intent of beautifying the landscape. Originally from China, leatherleaf mahonia is desirable to homeowners for its unique form, early flowering and attracting wildlife. The berries are especially palatable to birds which end up spreading the seeds far from the source. Leatherleaf holly needs to be watched closely since it could easily become established and create even more competition for desirable trees in forest settings. Due to its spiny leaves deer will most likely avoid browsing on it which gives it a leg up when compared to most native plant species.
To prevent the spread of leatherleaf mahonia, find alternatives, and eradicate the plants you find outside of a landscaped setting. Alternatives for leatherleaf mahonia include: winterberry holly, which has colorful red berries that attract birds throughout the winter, and American holly, which is another evergreen with spiny leaves that can be planted for privacy, security or beautification. Eradication is achieved through the pulling of seedlings, and cut stump application of herbicide to specimens which are too large to dig up or pull. Be careful since the spines on leaves are sharp and can cause injury, to be safe use basic precautions like gardening gloves, long pants/long sleeved shirts, and eye protection.
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For more information about Invasive Species of Concern in Maryland, visit www.mdinvasivesp.org
photos available electronically on request.