Contact: Tim Culbreth, Maryland Department of Natural Resources | TCulbreth@dnr.state.md.us
ANNAPOLIS, MD (January 19, 2012) – Some invasive species have a native counterpart whose niche they invade and then try to outcompete for resources. Norway maple is an example. It is a very shade tolerant tree like the native sugar maple and even in appearance the leaves resemble the sugar maple. As a result, it is often overlooked when it invades the forest until it has taken over and crowded out sugar maple as well as other native species such as oaks. There are other difference such as the shape and size of the seeds and the stoutness of its twigs that to a trained eye very noticeable making them easy to spot. Some invasive plant species however, and the Japanese angelica-tree in particular are almost exact copies of the native species for which it competes for space and resource. For this reason Japanese angelica tree, Aralia elata, has been chosen as the Invader of the Month.
Devils walking stick is an important species in Maryland since it is a popular landscaping specimen used to attract and feed birds with the abundant fruit it produces. When birds travel long distances and deposit the desired native seeds somewhere else, great. Unfortunately, birds are also a fast vector for transporting unwanted plants’ seeds over long distances, starting new populations of invasion. Understory trees always serve an important purpose of providing a healthy multi-layered forest, and soil stabilization. If Japanese angelica tree continues to expand, we’ll loose our native devils walking stick and many people won’t even notice the change.
The native species Hercules' club, Aralia spinosa, gets its name from the thick stem and stout thorns that cover the stem. An alternate name is the devil’s walking stick. Sporting one of the largest leaves in North America, they are bi and sometimes tri-pinnately compound. The differences between the two closely related species are few. The flower structures on Japanese angelica tree are shorter and lack a central axis found on the native Hercules' club. The other distinguishing feature is harder to detect and usually requires a hand lens. The main lateral vein on the leaflets runs all of the way to the margin or edge on Japanese angelica tree. On devils walking stick they diminish in size before reaching the tip.
Japanese angelica tree is commonly found planted as a landscaped species for privacy plantings. It is found escaped into the forest understory from nearby landscape plantings. In its native range of Asia, the Japanese angelica tree is found in forest edges, ravines, and hillsides.
If you have made the determination that you indeed have a Japanese angelica tree, it can be controlled by cutting the stems down to ground level in the spring and let it grow new shoots over the summer, then in the fall spray the fresh leaves with herbicide as recommended on the label.
For more information about Invasive Species of Concern in Maryland, visit www.mdinvasives.org