Japanese stiltgrass. Photo by Chuck Bargeron, University of Georgia, www. invasive.org

Photo by Chuck Bargeron, The University of Georgia, invasive.org

Updated: July 25, 2022

Maryland is home to a diverse variety of native trees, plants and insects, as well as some unwelcome non-native interlopers. Below are some of the most common questions we receive about both native and non-native species. Also see our Forest Threats pages and Woodland Management: Trees and Invasive Plants & Insects publications.

What types of trees or understory plant should I put in wetland and riparian areas?

Riparian forest buffers are areas that border bodies of water and should include a diversity of native, noninvasive woody trees, and shrubs (multiple species including hardwoods). Manage newly established buffers to allow the establishment of an organic duff layer and understory vegetation. The Zone 3 (outermost zone) filter strip may include warm season grasses. For fact sheets on riparian buffers, read University of Maryland Cooperative Extension's Fact Sheet #724, "An Introduction to the Riparian Forest Buffer."

Can riparian forest buffers be planted along streams that don’t flow year-round? Will they be eligible for subsidies?

Yes, from tiny creeks to major rivers, all waterways have a riparian zone, commonly known as the floodplain. The riparian zone stretches along each waterway and encompasses the area of annual or periodic flooding. The riparian zone is the waterway's buffer. Under normal conditions, this land and the natural vegetation growing on it traps sediments from upslope erosion, and filters out fertilizers and pesticides used on adjacent land. Check with your Soil Conservation District to determine if your stream qualifies for cost sharing. For a list of cost-share programs, consult "Riparian Buffer Financial Assistance Opportunities" (Fact Sheet #769) and the Stewardship Planning: Cost Share Assistance page.

How do I distinguish one tree from another?

Identifying trees is one of the greatest challenges for forest landowners. Certain key characteristics such as branching pattern and single or compound leaves can help. A simple guide called "Leaf Key to Common Trees in Maryland" is available here from the University of Maryland Extension.

I know a forester who identifies trees in winter by their bark, bud colors, and shapes. How can I learn this method of tree identification?

Most trees do have distinctive bark, buds and shapes, but this takes experience and practice. The best resource with an excellent key that should be a standard for all forest landowners is “Peterson Field Guides: Trees and Shrubs,” by George A. Petrides. However, if you want a field guide that just focuses on winter identification, we recommend “Woody Plants in Winter,” by Earl L. Core and Nelle P. Ammons. A good website for tree identification can be found at Virginia Tech's Department of Dendrology.

How do I identify grave threats from invasive and exotic species?

There are several resources for identifying and managing invasive species:

What is the best way to control invasive species?

The best control of invasive species is to not let them get started. However, in most cases it is impossible to eradicate invasive plants completely. Instead, we need to manage presence and limit or eliminate their spread. While using organic or mechanical controls are desired by many, most people have found that the judicious use of chemical herbicides are essential to have any significant impacts. For a variety of ways to control various invasive species visit the National Invasive Species Council.

What do spongy moth egg clusters and caterpillars look like? How are they different from eastern tent caterpillars?

The spongy moth (Lymantria dispar, formerly called the gypsy moth) is the most serious pest of oak trees in Maryland. They hatch in late April or early May. For more details and a picture of an egg cluster, see the University of Maryland Extension's Gypsy Moths and Caterpillars on Trees.

Eastern tent caterpillar is a common pest of wild cherry trees and hatch in early April. The eastern tent caterpillar is not as serious a threat to trees as the gypsy moth. Go here to see a comparison between the two. To learn more, see the University of Maryland Extension's "Eastern Tent Caterpillar and Forest Tent Caterpillar."

What are my options for spongy moth spraying?

You can use Bt (Bacillus thuringiensis) products or the chemical Dimillin to control young caterpillars of the spongy moth (Lymantria dispar, formerly called the gypsy moth) . If you are unable to spray your tree tops, hire a professional arborist. The Maryland Department of Agriculture maintains a list of licensed applicators. In large areas of forestation, community spraying is an option. For information on the University of Maryland Extension Gypsy Moth Suppression Program, visit the Maryland Department of Agriculture's Gypsy Moth Program.

What does poison ivy look like? How can you tell it from Virginia creeper in the winter?

Poison ivy has three leaves. The University of Maryland Extension's Home & Garden Information Center's "How to Identify Poison Ivy" has detailed information. By contrast, Virginia creeper leaves have long petioles, or foot-stalks, and are divided into five leaflets. The flowers are in small clusters, are yellowish-green in color, and open in July, a few at a time. The flowers are a favorite of bees and are succeeded by dark purplish-blue berries, about the size of a pea, which are ripe in October. For more information, visit here.

What does Japanese stiltgrass look like? How do I control it?

Japanese stiltgrass is an attractive, miniature bamboo-like grass that rapidly covers disturbed areas. It also can be identified by its lime-green color and a line of silvery hairs down the middle of the 2-3" long blade. It tolerates sun or dense shade and quickly invades areas left bare or disturbed by tilling or flooding. An annual grass, it builds up a large seed bank in the soil. To control the grass, pull it in early to mid-summer; be certain to pull before it goes to seed. If seeds have formed, bag and burn them or send them to the landfill. Mowing weekly or when it has just begun to flower may prevent the stilt grass from setting seed. Use glyphosate (the active ingredient in “Roundup”) or herbicidal soap (which is more environmentally-friendly but less effective) on large infestations. Perform follow-up control in the spring. For detailed information, read the Plant Conservation Alliance's Alien Plant Working Group "Least Wanted: Japanese Stiltgrass" publication here.

What is the difference between Red Maples and Norway Maples?

Red maples are native trees. Norway maples are non-native invasive species in Maryland, and can take over the native areas. For more information maple trees and to see images, visit https://bplant.org/compare/68-91.

How can you distinguish a walnut tree from a tree-of-heaven?

Tree-of-heaven (Ailanthus altissima), also known as ailanthus or Chinese sumac is an introduced weed tree that has become a common problem in many areas of the United States. Its leaves are very similar to those of black walnut but have a disagreeable odor when crushed. Ailanthus bark is smooth whereas black walnut is deeply furrowed. Tree-of-heaven has long been established in some urban and agricultural areas, and increasingly invades our forests, displacing more desirable native trees. To learn about Tree-of-heaven, see the links for Tree-of-Heaven at Forest Threats: Invasive Plants and Shrubs.