Negative Impacts of Invasive Plants

Glossy Buckthorn

Leaves with Emodin that kills plant growth

Asian Bittersweet

A climbing vine known for its bright orange berries and aggressive growth habit, often causing harm to native plants.

Morrow’s Honeysuckle

A highly invasive shrub with fragrant flowers and dark purple to black berries that can harm native plants.

Multiflora Rose

A thorny shrub introduced for erosion control and ornamental purposes, but known for invasively spreading and crowding out native vegetation.

Woody Nightshade

A perennial plant with purple flowers and toxic berries, often found in disturbed areas.

Japanese Barberry

A deciduous shrub with small yellow flowers that produces red berries. It is known for its invasive tendencies and ability to thrive in various environments.

Japanese Knotweed

a fast-growing, highly invasive perennial plant that is famous for its swollen and bamboo-like stems and extreme difficulty to control.

Common Reed

a large, perennial wetland grass that belongs to the Poaceae family. It is characterized by its tall, sturdy, cane-like stems, broad leaves, and large, feathery flower clusters that bloom at the top of the stalks.

Morrow’s Honeysuckle

Direct impact from shading out growth; indirect impact reduces pollen for bumblebees. Honeysuckle releases toxins with phenolic compounds, infecting ferns and spring beauties.Thicker stems allow easier predator access, decreasing songbird populations. Thick growth causes tick populations to rise, indirectly spreading diseases to deer, foxes, and moose.

Japanese Knotweed

It grows through cracks in asphalt, brickwork, concrete, and drains, severely damaging building foundations, walls, and flood defenses. Its presence can drastically lower property values, cause mortgage lenders to refuse financing, and result in expensive, multi-year removal costs. It forms dense thickets that block sunlight, outcompeting native plants and destroying local wildlife habitats. Because its roots die back in the winter, it leaves riverbanks and hillsides bare, making the soil highly vulnerable to severe erosion and flooding.

Common Reed

Displaces native plants: It forms dense, monotypic stands that choke out native vegetation and reduce plant biodiversity.Degrades wildlife habitat: The thick reed walls block movement and eliminate critical nesting and foraging grounds for birds, fish, and amphibians.Alters hydrology: It consumes large amounts of water and traps sediment, which dries out wetlands and changes natural water flow.Increases fire risks: The plant generates massive amounts of dry, dead biomass during winter, creating a severe fuel hazard for wildfires.

Asian Bittersweet

Strangles trees. vine twines tightly around tree trunks and branches as it grows. Over time, this squeezing action constricts the plant, cutting off the vital flow of water and nutrients.Mechanical Damage and Uprooting: The dense, heavy mass of woody vines adds substantial weight to the forest canopy. This makes host trees highly vulnerable to branch breakage and complete blow-over or uprooting during high winds, ice, or snowstorms.Smothering and Blocking Sunlight: The rapid-growing foliage forms thick mats that blanket the forest canopy and understory. This blocks sunlight from reaching native plants, suppressing photosynthesis and preventing forest regeneration.Genetic Displacement of Native Species: Asian bittersweet aggressively outcompetes the rare native American bittersweet. By swamping the native species with its prolific pollen, it frequently clashes with American Bittersweet threatening the native plant with genetic extinction.

Multiflora Rose

Smothers Native Plants: It forms dense thickets that block sunlight and crowd out native vegetation.Ruins Pastures: It invades grazing lands, replacing nutritious livestock forage with thorny brush.Blocks Land Access: Its sharp, tangled thorns create impenetrable barriers for livestock, wildlife, and humans.Harms Nesting Birds: It degrades native habitats, leading to higher nest predation rates for local birds.

Japanese Barberry

Amplifies Lyme Disease: Its dense, humid thickets provide ideal shelter for mice, creating optimal conditions that significantly increase blacklegged tick populations.Chokes Forest Understories: It forms thick, thorny monocultures that block light and outcompete native woodland plants and wildflowers.Alters Soil Chemistry: Its rapidly decomposing leaves increase soil nitrogen levels, which disrupts native soil organisms.Blocks Movement: Sharp, dense spines make thickets painful and impenetrable for people, livestock, and large wildlife.

Woody Nightshade

Poisons People and Animals: All parts of the plant contain toxic alkaloids that can cause severe illness or death if ingested by humans, pets, or livestock.Smothers Native Vegetation: It climbs aggressively over native shrubs and trees, blocking out sunlight and suffocating local plant life.Clogs Riparian Waterways: It grows across water surfaces, forming heavy mats that block fish passage and disrupt aquatic habitats.Increases Pressure on Natives: Because wildlife avoids eating this toxic plant, herbivores over-browse the remaining native plants.

Glossy Buckthorn

Displaces Native Understories: It leafs out early and retains its leaves late, creating a dense shade that suffocates native plants and stops forest tree regeneration.Harms Native Wildlife: Its prolific berries contain a natural laxative (emodin) that causes nutrient loss and malnutrition in birds that eat them.Alters Soil Chemistry: Its rapidly decomposing fallen leaves change the soil composition and pH, leaving bare patches that trigger soil erosion.Threatens Agriculture: It acts as a destructive alternate host for crop pests and diseases, including oat crown rust and the alfalfa mosaic virus.