Invasive species out-compete native plants.
Sometimes plants entice us to enjoy them with an abundance of flowers, brilliant colors or sweet fragrances. They use these lures to keep us from noticing the stealthy way they overtake more subtle but productive native species. Several examples of this invasive style of growth are showing up in wooded areas and back yards this time of year.
Garlic mustard (Alliaria petiolate)
Originally introduced from parts of Europe and Asia for food and medicinal purposes in the mid-1800s, this flowering plant has become extensively invasive in most parts of the US. It appears in early spring in the undergrowth of woodlands, forests, along roadways and anywhere there is a bare, moist or dry open area. Its presence overtakes many native plants.
Garlic Mustard
It is a biennial that takes 2 years to mature enough to produce flowers that provide seeds. During its first year of growth seeds germinate while the low-growing plants develop rosettes of leaves that can be hard to identify as an invasive. Its distinguishing fragrance of garlic when the leaves are crushed makes it easy to identify. A stalk appears the second year with small, white 4-petaled flowers atop the stalk. By the end of May seed pods that are dark and 4-sided develop and may each contain 22 or more seeds. The plant dies back by the end of June and the seeds are dispersed by humans or wildlife. The two-year cycle of germination and seed production continues as the plant spreads into new areas. Some research suggests that garlic mustard prohibits the growth of other plants in nearby areas. Seeds can survive as long as 5 years in the soil.
Management requires long-term persistence. Hand- pulling to remove roots before seeds develop can be effective for small infestations. Removing plants with flowers and/or seed heads should be bagged and disposed of in the trash, not in wood piles or compost areas. Chemical control can be effective but must be repeated due to the presence of seeds surviving in the soil.
Honeysuckle (Lonicera spp.)
Honeysuckle plants were likely introduced into North America as ornamentals from Asia beginning in the 1750s. Some varieties arrived through the 1800s, and as late as the mid-1900s some varieties were still sold for various purposes such as arboretum specimens, for soil erosion control and for wildlife cover and food. Some varieties are still sold in nursery centers in some states; they are all prohibited for sale in Connecticut. They have all escaped cultivation and the seeds are spread by birds and wildlife.
The Connecticut Invasive Plant Working Group lists 6 types of honeysuckle on the state’s list of invasive or potentially invasive non-native species. They include the vine Japanese honeysuckle (Lonicera japonica), and the shrubs Amur honeysuckle (L. maackii ), Morrow’s honeysuckle (L. morrowii), and Belle honeysuckle (L. x bella). These are all considered invasive. The two potentially invasive varieties include the shrubs Tatarian honeysuckle (L. tatarica) and Dwarf honeysuckle (L. xylosteum). Plants that appear on this list are prohibited from importation, movement, sale, purchase, transplanting, cultivation and distribution under CT General Statutes §22a-381d.
Morrow’s honeysuckle with flower buds in early spring
Honeysuckle shrubs are leggy, have an open form and range from 8-12 feet high. The vining variety can grow to 30 feet or more. Leaves typically are opposite, oblong and have smooth edges. The leaf upper and underside of some varieties are smooth, other varieties are hairy. Green berries appear in early spring. Small tubular flowers appear within the leaves in May and June and can be white, creamy, yellow or pink. Often several petals cluster to form a tube. If sliced open, stems on non-native varieties will have a brownish hollow center. Stems on native species will have a solid center. Depending on the species, berries can be orange to dark red and ripen in mid-summer until late fall.
Morrow’s honeysuckle blooming
True to their classification, these plants can form populations that out-compete and suppress the growth of native species. They can deplete the habitat of moisture, nutrients and sunlight. In addition, the nutrients in the berries of invasive species are lower than native varieties. This requires birds to spend time eating large amounts of less nutritious food and could affect their migration.
While honeysuckle population numbers are low in an area, hand removal of seedlings or young plants is best before berries ripen and birds begin to spread them while feeding. Controlled application of herbicides might be required for areas of large infestation. A biological control is not known.
Native deciduous plants such as chokeberry (Aronia ssp.), spicebush (Lindera benzoin) and dogwood (Cornus ssp.) will all provide food and cover for wildlife as alternatives to honeysuckle.
Winged Euonymus Euonymus alatus
Burning bush (Euonymus alatus), also known as winged euonymus, was introduced in the 1860s from Asia as an ornamental landscape plant. It is used extensively along roadsides, in parks and residential plantings and to beautify industrial parks all along the east coast and southern areas of the US.
Winged Euonymus
It is a multi-stemmed, branching shrub that usually grows 8-10 feet but when mature can grow to 20 ft. It is called “winged” because of the shape of its stems. Small, greenish flowers appear in spring, followed by a hard fruit which matures to a reddish purple in the fall. The leaves of the bush become a brilliant red, giving it the popular name “burning bush.”
It is on the Connecticut Invasive Plant Working Group list of invasive species but its sale is not prohibited. It produces hundreds of seeds annually which generate many seedlings under the parent plant as well as in areas removed from its parent, such as surrounding woodland areas and neighbors’ yards. It seeds are spread by wind and birds.
Its spread can be controlled manually, mechanically or chemically.
Jean Laughman
Uconnladybug's Blog 