Invasive plants in Maryland are regulated through a 2-tier system rather than a single flat ban, and according to the Code of Maryland Regulations, a Tier 1 invasive plant cannot legally be propagated, imported, transferred, sold, purchased, transported, or introduced anywhere in the state, while a Tier 2 plant can still be sold, but only alongside a required warning sign informing buyers of its invasive status. The regulation took effect April 11, 2016, and anyone already growing a Tier 1 woody plant in the ground at that time was given a 2-year phase-out window before full compliance was required.
That tiered structure has produced some genuinely interesting edge cases in how the rule actually applies, and according to University of Maryland’s Agricultural Law and Risk Management program, the restriction on Tier 1 plants doesn’t apply to a plant already growing on a property that’s being bought, sold, or leased, meaning someone who purchases a home with fig buttercup already established in the yard isn’t automatically in violation of the rule just for owning the land it grows on. Maryland has also continued to expand the list over time, and Scotch broom and heavenly bamboo were both added as Tier 2 species in 2017, several years after the original regulation took effect.
According to the University of Maryland Extension’s Home and Garden Information Center, the state’s invasive plant problem extends well beyond just the legally regulated Tier 1 and Tier 2 lists, since numerous other species remain widely documented as ecologically damaging even without carrying formal sale restrictions. What follows covers 24 invasive plants in Maryland, along with where each one grows and the data behind its spread.
Fig Buttercup
Fig buttercup, also called lesser celandine, produces glossy, heart-shaped leaves and bright yellow spring flowers on a low, spreading perennial that carpets the forest floor before dying back completely by early summer. It’s classified as a Tier 1 invasive plant in Maryland, meaning it can’t legally be propagated, sold, or transported anywhere in the state.
It grows throughout moist floodplain forests statewide, spreading through tiny underground tubers and bulblets that make even careful hand-pulling likely to leave behind fragments capable of regrowing.
Scotch Broom
Scotch broom produces bright yellow, pea-like flowers on a dense, woody shrub added to Maryland’s Tier 2 invasive plant list in 2017. Its seeds remain viable in the soil for decades, allowing infestations to persist and resprout long after visible plants have been removed.
It grows in scattered locations throughout Maryland, particularly along disturbed roadsides and sandy coastal plain habitat.
Heavenly Bamboo
Heavenly bamboo, also called nandina, produces evergreen, finely divided foliage and bright red berries on a shrub added to Maryland’s Tier 2 list alongside Scotch broom in 2017. Its berries contain compounds that have been linked to fatal cyanide poisoning in cedar waxwings and other birds that feed on them in large quantities.
It grows in scattered naturalized populations throughout Maryland, spreading via bird-dispersed seed from ornamental plantings into surrounding woodland edges.
Japanese Barberry
Japanese barberry produces small, oval leaves and bright red berries on a dense, spiny shrub originally valued for its ornamental foliage and deer resistance. Research has linked dense barberry thickets to higher populations of ticks carrying Lyme disease, since the humid microclimate beneath the shrub favors both tick survival and their small mammal hosts.
It grows throughout woodlands and forest edges across much of Maryland, forming dense stands that few native plants can successfully compete against.
Multiflora Rose
Multiflora rose produces arching, thorny canes lined with clusters of small white flowers, forming dense, nearly impassable thickets wherever it’s left unmanaged. A single mature shrub can produce close to 500,000 seeds in a year, widely dispersed by birds that eat its small red hips through fall and winter.
It grows throughout pastures, fence rows, and forest edges statewide, despite once being recommended by conservation agencies for erosion control and living fences.
Autumn Olive
Autumn olive produces bright green leaves that are distinctively silver underneath, with strongly fragrant cream to pale yellow flowers blooming each spring. Because it fixes atmospheric nitrogen through its root system, it can alter soil chemistry in ways that favor its own continued spread over native vegetation.
It grows throughout old fields, roadsides, and disturbed ground statewide, and its abundant, easily dispersed berries have made it one of the more difficult shrubs to eliminate once established.
Amur Honeysuckle
Amur honeysuckle leafs out earlier in spring and holds its leaves later into fall than most native shrubs, giving it a considerable head start in competing for available sunlight. Its abundant red berries are readily eaten and spread by birds, allowing new infestations to establish well beyond any original planting.
It grows throughout woodland edges and disturbed areas statewide, often forming dense understory thickets that block light from native tree seedlings.
Morrow’s Honeysuckle
Morrow’s honeysuckle closely resembles its Amur relative in small white, fading-to-yellow flowers and prolific red berries, distinguished by slightly hairier leaves and stems. Both species readily hybridize where their ranges overlap, complicating precise field identification.
It grows throughout woodland edges and disturbed areas across much of Maryland, forming dense thickets that suppress native plant regeneration.
Tatarian Honeysuckle
Tatarian honeysuckle produces pink to white flowers and red berries similar to its bush honeysuckle relatives, distinguished by smoother, hairless leaves. Its dense, multi-stemmed growth habit crowds out native shrubs wherever it establishes.
It grows throughout disturbed woodlands and fence rows across Maryland, spreading readily via bird-dispersed seed into surrounding natural areas.
Japanese Knotweed
Japanese knotweed produces hollow, bamboo-like stems that can push through cracks in pavement and foundations as a colony expands, spreading through an extensive underground rhizome network that extends well beyond the visible canes. Even a small fragment of rhizome left in the soil after removal attempts can regenerate an entirely new colony the following season.
It grows in scattered infestations throughout Maryland, particularly along riverbanks, roadsides, and disturbed urban lots.
Giant Hogweed
Giant hogweed produces enormous, deeply lobed leaves and a thick, hollow stem marked with distinctive purple blotches, capable of towering well over head height. Its sap contains compounds that react violently with sunlight on exposed skin, causing severe burns and blistering that can take months to fully heal.
It grows in scattered, closely monitored infestations in parts of Maryland, and residents are actively encouraged to report suspected sightings rather than attempt removal without proper protective equipment.
Oriental Bittersweet
Oriental bittersweet produces a woody, twining vine capable of climbing 60 feet or more into a tree canopy, eventually girdling and killing its host through a combination of constriction and accumulated weight. Its bright orange-yellow seed capsules split open in fall to reveal striking red seeds, a display that’s ironically helped spread the vine further since it remains popular for autumn wreaths.
It grows throughout forest edges and disturbed woodland across Maryland, increasingly displacing the considerably less aggressive American bittersweet native to the same region.
English Ivy
English ivy is an evergreen climbing and groundcover vine that spreads via both seed and rooting stems, planted for decades as low-maintenance landscaping before its invasive woodland behavior became widely recognized. Once a vine climbs high enough into full sun, its leaf shape changes from the familiar lobed juvenile form to a simpler, unlobed adult leaf capable of flowering and fruiting.
It grows throughout much of Maryland as both a cultivated groundcover and an escaped woodland invasive, forming a dense mat capable of smothering garden perennials and entire mature trees alike.
Wintercreeper
Wintercreeper is an evergreen, woody vine with aerial roots that let it climb into tree canopies, forming dense carpets on the forest floor that can overtop and shade out the trees it grows beneath. Its waxy leaves make it notably difficult to control even with herbicide application.
It grows throughout residential landscapes and adjacent woodlands statewide, having escaped widely from ornamental groundcover plantings into surrounding natural areas.
Garlic Mustard
Garlic mustard produces small clusters of white, 4-petaled flowers atop a biennial plant whose roots release chemicals into the surrounding soil that actively suppress the germination of nearby native plants. A single mother plant can produce thousands of seeds that remain viable in the soil for up to 10 years.
It grows throughout wooded areas across much of Maryland, threatening spring ephemerals like trilliums and trout lilies that can’t compete with its early, aggressive growth.
Common Reed
Common reed, referring to the invasive non-native lineage of Phragmites, forms dense, towering stands reaching 15 feet or more, displacing native marsh vegetation across huge areas of Chesapeake Bay wetland and shoreline. It spreads both by seed and by an extensive rhizome network capable of pushing out nearly everything else growing nearby.
It grows throughout tidal and freshwater wetlands statewide, forming monocultures so dense that almost nothing else can grow beneath the towering canopy it creates.
Purple Loosestrife
Purple loosestrife produces tall spikes of vivid magenta-purple flowers each summer, a display so attractive that it was originally introduced to gardens before its aggressive wetland behavior became apparent. A single mature plant can produce well over a million seeds in a season, an output that has allowed it to overwhelm native wetland vegetation across large areas.
It grows throughout marshes and wetland margins statewide, forming dense monocultures that crowd out the native plants waterfowl and other wildlife depend on.
Tree of Heaven
Tree of heaven produces large, compound leaves and grows remarkably fast even by invasive tree standards, with root sprouts capable of reaching several feet in their very first year alone. Its rapid, suckering growth habit makes it notoriously difficult to eliminate through cutting alone, since removing the visible trunk typically triggers even more vigorous regrowth.
It grows throughout much of Maryland, particularly along roadsides, rail corridors, and disturbed urban lots, and it also serves as the preferred host plant for the invasive spotted lanternfly.
Callery Pear
Callery pear, widely sold under ornamental cultivar names including Bradford pear, produces abundant white spring flowers followed by small, hard fruit that birds readily eat and disperse into surrounding natural areas. Its thorny, fast-growing wild seedlings form dense thickets in old fields and forest edges, a genuinely different plant than the tidy ornamental form sold at nurseries.
It’s an increasingly documented concern throughout much of Maryland, prompting several neighboring states to begin restricting its sale entirely.
Kudzu
Kudzu produces large, 3-lobed leaves on vigorous vines capable of growing 60 to 100 feet in a single season. Its massive underground tubers store enough energy to let the vine regrow persistently even after years of cutting and herbicide treatment.
It grows in scattered, actively managed infestations in parts of Maryland, considerably less established than in states further south but still aggressive wherever it takes hold.
Mile-a-Minute Vine
Mile-a-minute vine produces small clusters of tiny white flowers followed by distinctive metallic blue berries on a trailing, barbed vine capable of growing several inches per day. It was first reported in the mid-Atlantic region in contaminated nursery soil decades ago, and its seeds can remain dormant in the soil for up to 6 years.
It grows throughout much of Maryland, favoring moist soil and full sun along forest edges, wetlands, and streambanks.
Porcelain Berry
Porcelain berry produces small, inconspicuous greenish-white flower clusters followed by strikingly colored blue, purple, and turquoise berries on an aggressively twining vine. Its vigorous growth can smother shrubs and small trees within just a few growing seasons.
It grows throughout Maryland, particularly along forest edges and disturbed ground, forming dense tangles that block light from the native vegetation growing beneath it.
Wineberry
Wineberry produces small white flowers followed by bright red, raspberry-like fruit on canes covered in distinctive sticky, reddish, glandular hairs. Its edible, tart-sweet fruit is genuinely popular among foragers even as the plant displaces native blackberry and raspberry species in the same habitat.
It grows throughout Maryland, particularly along forest edges, spreading readily wherever birds disperse its seed after eating the fruit.
Chinese Silvergrass
Chinese silvergrass, also called Japanese silver grass or miscanthus, produces tall, arching clumps of narrow foliage topped with feathery, silvery-pink plumes in late summer. Widely sold as an ornamental grass, it readily self-seeds into surrounding fields and roadsides well beyond its original planting.
It grows in scattered naturalized populations throughout Maryland, forming dense stands that displace native meadow grasses and wildflowers.
Conclusion
Invasive plants in Maryland can spread through forests, wetlands, fields, roadsides, gardens, and other natural areas. They may compete with native vegetation for sunlight, water, nutrients, and space, while some species can also change the structure of local habitats.
Learning to identify invasive plants is an important step in limiting their spread. Early detection and regular monitoring can help find new infestations before they become widely established, making management more practical and helping reduce their impact on native vegetation.
Protecting Maryland’s natural areas requires continued attention from homeowners, gardeners, land managers, and local communities. Choosing non-invasive plants, preventing the movement of seeds and plant material, and managing established populations can help support healthy and diverse ecosystems across the state.