According to the Center for Invasive Species and Ecosystem Health, invasive plants are responsible for economic loss in excess of 1.1 billion dollars annually. Invasive species are defined as nonnative plants, animals and insects that reproduce and grow aggressively, causing harm to humans or the environment. Invasive plants spread by means of seed, suckers and underground growth. Vining invasive plants can cause a particular concern, due to their ability to reach all levels of the forest, choking out plants from the floor to the canopy.
Porcelain vine came to the United States from Asia in 1870. This invasive vine reproduces through seed spreading, as well as by sending out shoots. Porcelain vine is difficult to eradicate, because portions of cut vine that are in contact with soil can form new plants. Also known as amur peppervine, porcelain vine grows in dense mats over host plants, smothering them and blocking out sunlight. Porcelain vine is capable of growing 15 feet per year and is commonly found along streams and ponds, the edges of woodlands and other areas with consistent moisture and some sunlight. Porcelain vine is invasive throughout the entire northeastern region of the country and has a presence in some Mid-Atlantic states as well.
Brought to the United States from China in 1860, Oriental bittersweet is a deciduous vine capable of reaching lengths up to 60 feet. Oriental bittersweet can be distinguished from its noninvasive native counterpart. American bittersweet, by the placement of the flowers. American bittersweet produces flowers and berries at the tips of its branches, while Oriental bittersweet flowers where the leaves meet the stems. Oriental bittersweet seed is spread by birds that consume the berries appearing on the vine in winter. The vine also spreads by sending out suckers that grow vigorously to form new plants. Oriental bittersweet can vine around trees so tightly that the sap flow becomes restricted, and the tree dies. The vine also kills surrounding plants by outcompeting them for both water and nutrients where both are in short supply.
Japanese honeysuckle is a spring- and summer-flowering vine capable of reach 80 feet in length. Japanese honeysuckle produces small black berries that are consumed by birds. Birds fly to other areas and excrete the berry seeds along the way, spreading the honeysuckle far beyond its original planting location. The vines of Japanese honeysuckle can wrap around smaller trees, ultimately choking them out. Japanese honeysuckle also grows high in the tree canopy, forming a dense coverage that blocks out sunlight from plants below. The origins of Japanese honeysuckle in the United States can be traced back to 1806, when the plant was introduced in Long Island from its native habitat in Eastern Asia.
English ivy is a vining plant likely introduced to the United States from Europe. Despite widespread knowledge of the invasive nature of English ivy, many retailers continue to sell this ornamental vine. English ivy is a popular choice among gardeners because it offers quick coverage and stays green year-round. Unfortunately, the same attributes that attract homeowners to the plant are also responsible for the invasiveness of the vine. English Ivy forms a dense ground cover that blocks sunlight from native seedlings, preventing growth and ultimately killing the seedlings. The vine also climbs plants and trees, smothering them at all levels of the forest from the floor to the canopy. English Ivy can infest fragile ecosystems, such as salt marshes, as well as forests, fields and woodlands. In addition, English ivy can harbor bacterial leaf scorch, a pathogen that can attack native trees, including maples, elms and oaks.