Stiltgrass is an annual grass with spindly, shallow roots that can reach heights of a few feet in sunny, moist conditions but typically tops out at about a foot tall. Germinating in late spring, by July and August it crowds roadsides, drainage ditches, utility rights of way, trail edges, stream banks, and just about any disturbed site where a little sunlight interrupts the shade.

Where is it found in the park?

You will encounter stiltgrass in all or most park units, especially along trail edges or visible in forest openings. Its full invasive potential is on display in The Wetlands as well as Pony Pasture. Consecutive years of treatment have curbed its abundance and spread. To pick stiltgrass out from the crowd, look for smooth-edged lance-shaped leaves about 2 inches long and about half an inch wide, well-spaced alternately on stems, with a distinctive silver “mid-rib” (line or stripe) along the length of the leaf. Stems often branch in multiples from the base.

How it’s harmful:

Stiltgrass is an aggressive invasive species that spreads rapidly thanks to its abundant production of seeds that spread locally and are dispersed distantly by people and animals—especially deer—and by flooding when stiltgrass invades areas adjacent to streams and rivers while stormwater helps to spread stiltgrass along roadsides. A single plant will produce as many as a thousand seeds in its one season of life and those seeds can remain viable (capable of germination) for up to five to seven years. Stiltgrass forms ‘monocultures’ along forest edges and in forest canopy openings; the result is a loss of diversity of native plant species and all the wildlife that depend upon them.

Important to know:

Stiltgrass proves that “timing is everything” when it comes to reducing its damage. Pull, cut, or treat it in in late July and August every year before it flowers and seeds, and you can eliminate small populations and reduce larger ones. But cut or pull stiltgrass after it has gone to seed and you will have aided and abetted its spread. Do the same too early and stiltgrass will respond with vigorous new growth. Also: stiltgrass and other invasive plants are another good reason to abide by the law and keep your dog leashed. Like deer, dogs are a free ride for hitchhiking invasive seeds.

For accurate identification and more information:

Alabama Cooperative Extension System: Field Guide to The Identification of Japanese Stiltgrass »
Blue Ridge Prism: Japanese Stiltgrass »

Where is it found in the park?

Perilla is likely present in most park units, but is most visible at entrances, edges of parking lots, and along main trails and access roads. It frequently occurs with stiltgrass.

How it’s harmful:

Perilla forms extensive patches that displace native plants including summer wildflowers, reducing host and nectar species for pollinators. While not an issue in the park system, it is known to be toxic to horses and cattle, which makes it a priority for eradication in pastures.

Important to know:

If you have perilla in your yard or along the edge of your street, you can hand pull it before it flowers and seeds. Repeat each year.

To learn more:

Mississippi State Univeristy: Perilla Mint (Perilla frutescens) »

Where is it found in the park?

While Tree of Heaven occurs throughout the JRPS, it has been most abundant at Belle Isle, Manchester Climbing Wall, Ancarrow’s Landing and Reedy Creek to the Lee Bridge. The JRPS and task force have focused control efforts to remove many Tree of Heaven and curb its spread. Beyond the park look for Tree of Heaven along the edges of roadways where it often forms thickets.

How it’s harmful:

Tree of Heaven matures early and grows vigorously, reproducing by abundant seed product and clonal reproduction (root-suckering). It also produces “allelopathic” chemicals that suppress the growth of other plants. Tree of Heaven forms monocultures that exclude native species, degrading habitat. It is the preferred host plant for the invasive Spotted Lanternfly.

Important to know:

The native species Black Walnut, hickories, sumacs, and Ash have been mistaken for invasive Tree of Heaven. Tree of Heaven requires chemical treatment to control it. Cutting Tree of Heaven without treatment triggers regrowth and spread.

Where is it found in the park?

Abundant in the understory in many parts of the park system, and the surrounding neighborhoods, Chinese Privet is at its most dominant at Ancarrow’s Landing and Great Shiplock. There and in other park units including Pony Pasture and The Wetlands, focused control efforts have significantly reduced populations of Chinese Privet.

How it’s harmful:

Chinese Privet forms exceptionally dense thickets through abundant seed production and lateral root sprouting, eliminating native species and changing the “community structure” in natural areas.

Important to know:

Chinese Privet is one of several invasive privets along with Garden Privet (Ligustrum ovalifolium), Border Privet (Ligustrum obtusifolium) and European Privet (Ligustrum vulgare). There are no native species in the genus Ligustrum in North America; if it’s a Ligustrum/Privet, it is an introduced species.

Where is it found in the park?

Huguenot Flatwater, Pony Pasture, and other park units. Burning bush went mostly unobserved in the 2015 baseline study surveys. Does this mean it wasn’t present at that time? No. It is more likely that burning bush was obscured by the greater density of more dominant invasive shrub species and that it was more difficult to distinguish in its summer foliage compared to its fiery winter appearance. Invasive managers are adding burning bush to their priority list to ensure it does not benefit from the removal of Chinese privet, Amur honeysuckle, and other invasive shrubs.

How it’s harmful:

Like other invasive shrub species, burning bush forms dense thickets displacing native woody and herbaceous species.

Important to know:

Just because something is advertised as having spectacular fall color and appealing berries doesn’t mean it’s a good landscaping choice. The abundant burning bush in Pony Pasture is adjacent to a neighborhood with . . . burning bush; birds that feed on its berries are effective spreaders of its abundant seeds and dumping of yard waste also may have been a contributing factor. Burning bush will resprout vigorously from root systems of shrubs that are cut down but not treated.

For identification and more information:
Blue Ridge PRISM »
Penn State Extension »

Where is it found in the park?

Just about everywhere. Huguenot Flatwater, Pony Pasture and The Wetlands suffer nearly universal ground coverage of this evergreen vine, along with its pal, English ivy (the two have a lot in common). These park units also display the effects winter creeper (and ivy) have on trees.

How it’s harmful:

Winter creeper forms dense ‘monocultures’ on the forest floor through its runners (or stems) along the ground that continuously grow roots. It displaces native species, particularly herbaceous plants including wildflowers, and can inhibit forest succession. Research has shown winter creeper’s damage to soil chemistry and biology, impacts that persist after removal.

Winter creeper attaches to and climbs trees, maturing to form densely intertwined vines that grow to be as large as small trees themselves. Growing up into the tree canopy allows it to flower, fruit, and spread distantly through seed dispersal. Winter creeper (and English ivy) infestations weaken trees and damage their protective bark. Infestations rob a tree of soil nutrients and water, invite disease and decay by trapping moisture against the bark, and restrict a tree’s “bend, not break” flexibility. Trees weighed down with winter creeper (or ivy) – which often form ‘sails’ or ‘curtains’ of free-hanging vines – are more likely to topple in a storm, especially if heavy ice or snow is involved.

Important to know:

Like many invasives, winter creeper is still available for sale and often encouraged as a landscaping option. Please do not plant winter creeper.

Winter creeper and English ivy are species that can be controlled and reduced through manual removal of  groundcover. Winter is the ideal season for this method because herbaceous plants–like spring and summer wildflowers–are dormant. But take care: Work vines thoroughly out of the ground with as little breakage as possible  and allow to dry out without making contact with soil (they will re-root and keep growing). If you intend to dispose of the vine debris in the garbage, be sure to do so in tightly tied bags. And be gentle: critters like frogs, salamanders, and box turtles hibernate in the upper layers of soil and leaf litter.

For identification and more information:
Mid-Atlantic Invaders Tool »
University of GA Center for Invasive Species and Ecosystem Health »

An early spring flowering perennial introduced to North America as an ornamental during the 1800s from parts of Europe, Asia, and northern Africa, Fig buttercup is now outcompeting native wildflowers in a park near you. Fig buttercup does produce seeds, but its main mode of reproduction is through its tuberous root system and stem bulblets, any fragment of which will generate a new plant.

Where is it found in the park?

The densest and most widespread populations of Fig buttercup occur in The Wetlands and Pony Pasture although it also occurs at Ancarrow’s Landing, near Reedy Creek, on Belle Isle, and in Huguenot Flatwater where expansive ‘reservoirs’ of Fig buttercup are common on private property along upstream tributaries. It was first identified in 2015 in The Wetlands where it had spread from nearby yards helped by stormwater runoff.

How it’s harmful:

Fig buttercup emerges in winter (as early as December in Richmond) and spreads rapidly, forming carpets of dense foliage  that prevent the seeds of native spring wildflowers and other native plants from germinating and growing. Fig buttercup most commonly spreads in floodplains, wetlands, and riparian areas where stream and river action transport the plant’s parts to gain a foothold in new locations.

Important to know:

Disturbing the underground tubers of Fig buttercup adds to the problem. Only in cases of a small number of scattered individual plants is digging up Fig buttercup considered a method of control; the entire plant must be thoroughly removed and securely bagged for disposal.  Fig buttercup has a narrow treatment window because it disappears by early May and because the later emergence of surviving populations of native plants must be protected.

For identification and more information including control guidance:

Penn State Extension: Don’t be Deceived by This Beguiling Springtime Plant »
USDA: Fig Buttercup | National Invasive Species Information Center »

Where is it found in the park?

Ancarrow’s Landing, Belle Isle, Pony Pasture, and probably most other park units.

How it’s harmful:

Garlic mustard can form expansive monocultures, displacing a natural community’s native species, particularly wildflowers. It is an allelopathic species meaning it produces its own chemicals that inhibit the growth of other plants and cause other damaging effects. Research has implicated Garlic mustard’s toxicity in the decline of butterfly species that rely on the toothworts – native wildflowers in the same genus as Garlic mustard.

Important to know:

Garlic mustard root system spreads from a taproot; this makes mature plants receptive to hand-pulling. Manual removal must occur before seed-set. Though remnants of the roots will not regenerate if pulled-up plants are left behind, Garlic mustard flowers have the capacity to form seeds even after removal so mature plants should be tightly bagged and disposed of. Garlic mustard has native lookalikes, particularly golden ragwort whose leaves at first glance resemble those of Garlic mustard.

For identification and more information including control guidance:

Blue Ridge PRISM: Garlic Mustard Fact Sheet »
Penn State Extension: Garlic Mustard: a ubiquitous invasive weed »