Field Guide
Invasive Plants to Watch in Central Ohio
The Upper Scioto watershed and Central Ohio's 17 counties harbor a growing roster of invasive plants. Some arrived as ornamental escapes; others hitched rides in fill dirt or spread from nearby disturbed areas. A handful of species now dominate yards, woodlands, and roadsides across the region, outcompeting native plants and reshaping entire plant communities. Learning to recognize them, and understanding where they thrive, is the first step toward protecting your land and the species that depend on it.
The watchlist
Amur honeysuckle (bush honeysuckle)
Amur honeysuckle is a deciduous shrub that leafs out remarkably early in spring, before native plants have awakened. Its opposite leaves are simple and oval; small fragrant flowers range from white to pale pink, followed by red berries that birds consume and disperse widely. The plant forms dense, nearly impenetrable thickets in woodlands, field edges, and disturbed areas across Central Ohio. Once established, it shades out native wildflowers and understory shrubs, fracturing the layered structure that native plant communities depend on.
Callery pear
Planted extensively throughout Central Ohio as a street tree and suburban ornamental in the 1990s and 2000s, Callery pear is a fast-growing tree with a narrow pyramidal crown and abundant small white flowers in spring. Its opposite leaves turn dark red to burgundy in autumn, and it produces small hard fruit that persists into winter. Over the past decade, this tree has begun escaping cultivation across the region, spreading into woodlands and natural areas where it crowds out native trees and shrubs, particularly along the Scioto river corridors. See our full Callery pear profile for identification and removal.
Garlic mustard
Garlic mustard is a biennial that forms a low rosette of rounded leaves in its first year, then bolts into a 1- to 3-foot-tall plant with triangular upper leaves and small white flowers in its second spring. Crush the leaves or dig up a root and the smell is unmistakable, pure garlic. It has become one of the most aggressive invasives in Central Ohio's woodlands, releasing chemicals from its roots that inhibit the growth of native wildflowers and seedlings. Dense garlic mustard populations often coincide with missing spring ephemerals like trilliums and bloodroot.
Japanese knotweed
Japanese knotweed is a tall herbaceous perennial reaching 8 to 10 feet by midsummer, with large heart-shaped leaves arranged alternately on jointed, hollow stems that resemble bamboo. Small white or greenish flowers appear in late summer, but the real problem lies underground, an extensive rhizome network that spreads with alarming speed and depth. It dominates riparian zones and disturbed areas along Central Ohio roadsides and stream corridors, forming dense monoculture stands. Fragments of rhizome as small as a fingernail can regenerate into new plants, making removal extraordinarily difficult.
Tree-of-heaven (ailanthus)
Tree-of-heaven is a fast-growing deciduous tree with large compound leaves made up of 20 or more leaflets; crush the leaf and you'll detect an acrid, unpleasant smell. The tree produces clusters of small greenish flowers in early summer, followed by abundant flat winged seeds that spiral down in late fall. It thrives in disturbed and compacted soils and can emerge through pavement cracks, crowding out native trees in old fields and woodland edges throughout Central Ohio. Like garlic mustard, it releases chemicals that inhibit competing plants.
Lesser celandine
Lesser celandine is a low-growing perennial wildflower that bears a deceptive resemblance to native spring ephemerals, with heart-shaped leaves and glossy, bright yellow cup-shaped flowers blooming in early spring. The plant spreads primarily through small bulblets that form in leaf axils and break off to establish new plants in nearby soil. It carpets floodplain woodlands and wetland margins across the Upper Scioto watershed with a dense, nearly impenetrable mat. Because it flowers and grows before native spring wildflowers emerge from dormancy, it starves them of light and resources before they can compete.
Winter creeper
Winter creeper is an evergreen groundcover and climbing vine with small opposite rounded leaves, often with white or yellow variegation. It persists green year-round, creeping across the forest floor and climbing tree trunks and shrubs with aerial rootlets, visible even in winter when deciduous forests are bare. It smothers native groundcovers and tree seedlings, and as it climbs it girdles saplings, cutting off water and nutrient flow. Because it remains actively growing when most forest plants are dormant, it monopolizes light and moisture during the season when native plants are most vulnerable.
| Species | Typical habitat |
|---|---|
| Amur honeysuckle | Woodlands, field edges, disturbed areas, yards and hedgerows |
| Callery pear | Escape from urban plantings; spreading into woodlands and riparian zones |
| Garlic mustard | Deciduous and mixed woodlands, floodplain forests, shaded areas |
| Japanese knotweed | Stream corridors, riparian zones, disturbed roadsides |
| Tree-of-heaven | Disturbed and compacted soils, old fields, development margins |
| Lesser celandine | Floodplain woodlands, wetland margins, riparian areas |
| Winter creeper | Woodlands, hedgerows, disturbed areas, shaded landscapes |
Frequently Asked Questions
What are the most common invasive plants in Central Ohio?
Amur honeysuckle is probably the most widespread invasive shrub across the region, appearing in nearly every woodland edge, old field, and disturbed area. Garlic mustard dominates the understory of many Central Ohio deciduous forests, particularly where disturbance or deer browse have weakened native plant communities. Japanese knotweed, while more localized, is extremely aggressive in riparian corridors and along streams throughout the watershed. Callery pear, planted extensively in urban and suburban landscapes decades ago, is now establishing in natural areas. Lesser celandine and winter creeper are also prevalent in woodlands, especially in wetter or shaded sites. Tree-of-heaven thrives in disturbed soils around development margins.
How do I identify an invasive plant?
Start with the fundamentals: leaf arrangement (opposite or alternate), leaf shape and texture, and flowering time and color. Many invasive plants have distinctive smells, crush the leaves of garlic mustard and tree-of-heaven to confirm. Watch for unusual growth patterns, like the very early leafing-out of honeysuckle or the bamboo-like jointed stems of Japanese knotweed. Notice the plant's habitat: some invaders favor shaded woodlands, others stream corridors or disturbed soils. If a plant is present in unusual density or seems to be outcompeting everything around it, it may well be invasive. Take photographs and visit our species pages for detailed identification help specific to Central Ohio.
Which invasive plants are the worst for Ohio yards?
Amur honeysuckle and winter creeper are two of the most troublesome for yards across Central Ohio, especially in older or wooded neighborhoods where they spread from adjacent woods. Honeysuckle invades from neighboring properties and forms large, impenetrable stands within years. Winter creeper climbs trees, smothers groundcovers, and persists year-round, making removal time-consuming. Japanese knotweed is less common in residential yards but far more difficult to control once present, its rhizomes will regenerate from tiny fragments left behind. Garlic mustard tends to be managed more easily but spreads rapidly in shaded moist areas. For most homeowners, prevention is more practical than eradication; keeping invasives from establishing is vastly easier than trying to eliminate them once they take hold.
Learn more
Each of these species has deeper ecological and identification details worth knowing. Visit our individual species pages to understand their history, biology, and control approaches tailored to Central Ohio. For guidance on restoring your land with native alternatives, explore our native plant guide. If you encounter an invasive plant you're unsure about, take photos and document the location. Your observations help track the spread and inform management priorities across the region.