Forest Health

The white mulberry reached our shores during the colonial period. This invasive plant is found in every Maryland county.

Winter Creeper arrived in the U.S. in 1907 and has since spread throughout much of the eastern states. This vigorous evergreen perennial vine can grow in a variety of conditions, can grow into shrub thickets up to 3 feet high, and may climb into trees more than 60 feet above the ground.

Chinese and Japanese Wisterias arrived in the U.S. in the early 1800s and have since spread to habitats across much of the eastern states. These twining and climbing vines can not only strangle and shade out trees, but can form dense thickets that suppress other native species.

Afforestation is the process of planting trees in formerly open space. Because trees take time to mature, it is important to ensure that the seedlings have sufficient light and nutrients to grow. This often involves controlling growth of other species within the planting area, including invasive species such as the distinctive Johnsongrass. And once established in an area, Johnsongrass can out-compete many other species for nutrients and over-top them to rob them of sunlight.

Porcelain-berry is a deciduous, climbing, woody vine introduced from northeast Asia in the 1870s. It became popular for its tolerance of adverse conditions and its ability to provide ground cover. However, it is an aggressive plant that invades damp, shady areas such as streambanks, forest edges, pond margins, and disturbed areas, and forms dense mats that crowds out native vegetation.

Tree-of-heaven has been receiving a significant amount of attention lately, and not just because it is a fast-spreading invader of woodlands throughout the mid-Atlantic states and beyond. the recent discovery of a new invasive insect in Pennsylvania, and its subsequent spread into adjoining areas, has lent new voice to advocates for the plant’s removal. Spotted Lanternfly, a recent arrival from Asia prefers tree-of-heaven as its host. This has led to an increased movement to remove tree-of-heaven from the landscape.

Winged euonymus is not widespread in the mid-Atlantic. Its greatest reported infestations are in the Midwest and Northeast. It has been found in much of central and southern Pennsylvania, far northern Delaware, southwestern Virginia, north-central West Virginia, and the greater Washington DC area.

Butterflybush is a rarity among non-native, invasive species. It has a wide variety of cultivars and a wide range of supporters among retail outlets as well as some environmental observers. It is also benefitting from positive public relations related to the decline of butterflies. However, it is indeed invasive, and contributes to (rather than mitigates) the decline of pollinators.

Japanese knotweed is an upright, shrubby, herbaceous perennial plant that can grow to over ten feet in height. It commonly invades disturbed areas with full or mostly full sunlight, such as roadsides. However, it can tolerate shade, as well as high temperatures, high salinity, and drought.

Kudzu is a deciduous, climbing, semi-woody perennial vine that grows 35 to 100 feet long. It grows via runners, rhizomes, and from nearly every node that touches the ground. It spreads most rapidly in open areas, including disturbed areas such as abandoned fields, roadsides, and forest edges.