Overview:

Water primrose is a perennial aquatic herb that grows roots in areas of shallow water to about 1 m deep. It grows in dense mats along shorelines and out into the water. It favors the margins of lakes, ponds, ditches and streams. It blooms throughout the summer and can withstand slowly flowing water. Water primrose can be controlled by cutting or by covering with opaque material.

Plant Identification:

Water primrose can be identified by its sprawling growth habit. Leaves are alternate and slightly hairy. Early growth consists of rosette-like clusters of rounded (suborbicular to spatulate) leaves on the water surface. It has showy yellow flowers which typically have five petals. The stems also lengthen at flowering and grow upright. Flowering stems can rise to three feet above the water surface. The fruit is a cylindrical capsule. The roots are feathery at the nodes, and they dangle into the water. White, spongy aerenchymas roots are also found at the nodes.

Distribution of water primrose sightings in the United States. L. hexapetala has not yet been recorded in Fairfax County.

Distribution of water primrose sightings in the Fairfax County area on iNaturalist. Available online, last accessed April 26, 2022.

Sources:
Alvesgaspar, 2011, Wikimedia Commons; File:Ludwigia July 2011-1.jpg - Wikimedia Commons Bill1953, 2020, Seedbox from Rock Creek, Little Rock, AR, USA on July 07, 2020 at 09:57 AM by bill1953. Disturbed area, partial sun, near creek. · iNaturalist

Overview:

Two-horned trapa is a floating, rooted, aquatic annual species. It has been found in rivers, fresh tidal bays, and ponds throughout Fairfax County. The plant may easily be pulled up and bagged or left high on the shore to dry and die.

Plant Identification:

It has submerged, flexuous stems and roots that are anchored into mud and extend upwards to the surface of the water. It has a rosette of floating, alternate, fan-shaped leaves, each leaf having a slightly inflated leaf stem and doubly serrated or toothed leaf margins. The leaf surface is green above and red below; submerged leaves are opposite, linear, and die back to be replaced by roots. Its flowers are solitary, small, have reddish sepals, pale to very pale pink petals, and sprout in the center of the rosette. Two-horned trapa begins flowering in June and continues to do so until first frost. Fruits and seeds are a large drupe or "nut" with sharp spikes.

Distribution of water chestnut sightings in Fairfax County.

Trapa bispinosa Early Detection and Eradication

Nonindigenous Aquatic Species (USGS)

Sources:
Pfingsten & Rybicki, 2022, NAS - Nonindigenous Aquatic Species. See Protect our Waters (fairfaxcounty.gov) and Swearingen, J.M. and J.P. Fulton. 2022. Plant Invaders of Mid-Atlantic Natural Areas, Field Guide. Passiflora Press, Cheverly, MD. 200 pp., and Digital Atlas of the Virginia Flora for more information about Trapa.

Overview:

Fountain grass, also known as Chinese fountain grass, is a popular garden grass. Fountain grass is prized for its bottle-brush inflorescence and arching ‘fountain-like’ leaves. The species is commonly found naturalizing in lawns and waste spaces, old fields, wet meadows, roadsides and golf courses. As a relatively new invader in the northeast, little is known about the ecological impacts of fountain grass in this region. Capable of reproducing both via seed and underground runners, this species has been identified as invasive in several mid-Atlantic states, where it readily spreads into natural areas. The species tendency to form dense clumps can cause changes in the diversity of the herbaceous layer in the communities it invades.

There is very little information available on hand pulling fountain grass to control invasive populations. Very small populations may be effectively controlled by careful hand pulling. New seedlings can be hand pulled or sprayed. Mowing and other forms of cutting will eliminate seed rain but will not eradicate fountain grass. Landscape fabric has been utilized in combination with other control methods to achieve some measure of success. Controlled populations should be revisited for several years to ensure no germination of new seedlings or re-sprouting has occurred.

Plant Identification:

Thin blades (about 0.25 in. wide) radiate directly from basal crowns. Blades are medium green, fine textured and arching. Foliage starts to turn shades of yellow, chartreuse, and amber in late summer before frost; after frosts and freezes, it matures to a light tan in autumn. Growing approximately two to three feet in height, the species is most conspicuous when it blooms towards the end of the summer and fall, producing pinkish white to brown flowering spikes. Flowering occurs in late August to early September. Flowers grow above the grass blades on thin stalks and occur in 5-inch-long clusters that look like thin bottle-brushes. They quickly change from green to pink and violet to tan. Fountain grass produces an abundance of brown caryopses from summer to autumn fruits will break open after a few hard freezes, scattering seeds which can form new plants Seed is largely dispersed by wind, however, due to the seeds’ long bristles, dispersal by mammals is possible, as well.

Regional distribution of Fountain Grass

Sources:
Pennisetum alopecuroides | Lower Hudson Partnership for Regional Invasive Species Management. Brookman, 2015, Pennisetum alopecuroides/NJ - Bugwoodwiki

Overview:

Wavyleaf basketgrass is a low-lying, trailing perennial grass that is less than one foot tall. The plant should be pulled and bagged. Please be careful when plant is seeding and check your boots and pants for seeds.  [include image of the flyer and link to download final wavyleaf basketgrass flyer.

Plant Identification:

Its leaf blades are about 0.5 to 1.5 inch wide and 1.5 to 4 in. long, have elongated pointed tips and are rippled or undulating. It is noticeably hairy where the leaf attaches to the stem, although the hairs are very short. Individual stems connect to each other underground. When the plant blooms, from mid-July through November, the grass sends up a spike that has seeds along it. Seeds are sticky and can stick to clothes, boots, fur, etc. The plant tends to spread horizontally across the forest floor.

Distribution of Wavyleaf sightings in Fairfax County.

Overview:

Asiatic false hawksbeard is a cosmopolitan herb that often grows as an agricultural and environmental weed. It is commonly found in disturbed areas, wastelands, roadsides, abandoned pastures, lawns, cultivated fields and forest margins, but it is also able to penetrate intact or minimally disturbed natural areas. This species is a prolific seed producer, and its seeds can be easily dispersed by wind and water or as contaminant in soil or crop and grass seeds. Young plants can be easily pulled out before they go to seed, taking care to remove all roots and stems. As the plant gets older and more firmly rooted, they cannot be pulled out without breaking off the stems, which will then regrow. Plants which are mowed above soil level recover quickly.

Plant Identification:

Asiatic false hawksbeard seedlings form a rosette resembling a small sow thistle (Sonchus spp.), but leaves are hairy. Upper leaves are more linear and lack a stalk, and a milky sap is emitted when leaves are torn. In contrast to dandelion, narrowleaf hawksbeard plants have leaves on the flowering stem, and plants can become highly branched. In the rosette stage (i.e., before the flowering stem has bolted upward), it is much trickier to differentiate between narrowleaf hawksbeard and dandelion. Inflorescence stalk is generally leafless (but occasionally with up to 3 leaves), branched at the top, and 6 to 15 in. (occasionally to 3 feet) tall. Flowers are yellow, dandelion-like but only about 1/2 inch in diameter. Seed heads are dandelion-like, about 1/4 to 1/2 in. in diameter, and seeds are wind dispersed.

Distribution of Asiatic false hawksbeard sightings in Fairfax County.

Sources:
Youngia japonica (oriental false hawksbeard) (cabi.org)].
Hawksbeard - Youngia japonica | North Carolina Extension Gardener Plant Toolbox (ncsu.edu)

Overview:

Houttuynia cordata, also known as fish mint, fish leaf, rainbow plant, chameleon plant, heart leaf, fish wort, or Chinese lizard tail, is an herbaceous perennial plant native to Southeast Asia. It grows in moist, shady locations and is considered an invasive plant because of its ability to regrow rhizomes from any segment of its foliage. It is difficult to eradicate as its roots run deep and actively spread.

Plant Identification:

Chameleon plant is a flowering plant that can grow to 2 ft. 0 in. - 3 ft. 3 in. high and spread up to 3 ft. 3 in. The leaves are alternate, and broadly heart-shaped, 1 1⁄2–3 1⁄2 in. long and 1–3 in. broad. Its flowers are greenish-yellow and borne on a terminal spike. It normally blooms in the summer.

Distribution of Chameleon plant in Fairfax County.

Source:
Chameleon Plant (Houttuynia cordata) (inaturalist.org)

Overview:

Crow dipper (or crowdipper) is native to China, Japan, and Korea. However, it also grows as an invasive weed in parts of Europe (Austria, Germany) and in North America (California, Ontario, the northeastern United States) It can grow in grasslands, secondary forests, wastelands, and cultivated areas. Because its stem regenerates from a corm that resides in. below the soil’s surface, hand-pulling is rarely effective in ridding a garden area of crow dipper. Use a digging tool deep enough in the soil (a few in.) to excavate the entire plant. Success is achieved if the removed plant still has a spherical corm attached to its long white stem. Bag and dispose of plant material.

Plant Identification:

The leaves are trifoliate, and the flowers are of the spathe and spadix form that is typical of plants in the family Araceae. The plant spreads by rhizomes, and there are also small bulblets (also known as bulbils) at the base of each leaf. Flowers are born in spring.

Distribution of Asiatic false hawksbeard sightings in Fairfax County.

Sources:
Crowdipper (Pinellia ternata) · iNaturalist, citing Wikipedia, see Pinellia ternata in Flora of China @ efloras.org for technical details on how to identify this plant. Observations of Crow dipper near the Fairfax County area on iNaturalist.

Overview:

Elecampane (Inula helenium, also known as elfwort, elf dock, wild sunflower, horseheal, velvet dock, alant, yellow starwort, inula, inul, horse elder, and scabwort) is a coarse, herbaceous perennial in the aster family (Asteraceae) growing from 2 to 8 feet in height and bearing resemblance to sunflowers. It grows most often in rich, moist, well-drained calcareous soils and prefers sunlight to partial shade locations. It can be found along roadsides, open woodlands, grasslands, fields, meadows and damp pastures. It occupies space that desirable indigenous species require and compete for competes for available resources, such as sunlight. Remove small infestations by hand pulling or digging. Use gloves and remove entire root system. Remove before flower set in spring.

Plant Identification:

Upon germination, the plant produces a basal rosette of leaves and may continue to produce only basal leaves for several years until it is sufficiently large enough to bolt. The basal leaves are born on long petioles and are from 10 to 20 in. long and 4 to 8 in. wide. Leaves are rough above and soft with velvety white hairs below. Long slender ray flowers project out from bright yellow flower heads, 2 to 4 in. in diameter and flower July to September. Flower heads are single or in small groups at the end of the long stalks. The yellow root is large and fleshy, about 6 in. long and an inch or two thick, with lateral rootlets 6 to 12 in. long. It reproduces vegetatively and from seed.

Observations of Elecampane in the Fairfax County area on iNaturalist.

Source:
USDA Forest Service - Elecampane.doc (invasive.org)

Overview:

Giant hogweed is a toxic perennial. The sap from this plant may cause serious irritation and blisters on the skin. This plant may be easily confused with native Elderberry (Sambucas nigra). A member of the parsley family, giant hogweed’s most impressive characteristic is its massive size. Spreading by seed, giant hogweed has escaped into numerous backyards, ravines, parks, abandoned lots, streams, woods, and roadsides. It can crowd out other plants and take over natural areas, especially in moist areas such as stream sides. Giant hogweed can be cut or pulled; however, exercise extreme caution when handling.

Plant Identification:

Giant hogweed reaches a height of 10 to 15 feet when in flower and has hollow stems, 2 to 4 in. in diameter, with dark reddish-purple raised spots and stiff bristle-like hairs. Coarse white hairs are also at the base of the leaf stalk. The sharply incised compound leaves grow up to 5 feet in width. Giant hogweed blooms from mid-May through July, with numerous white flowers clustered in an umbrella-shaped head that is up to 2.5 feet in diameter across its flat top. The plant produces flattened, 3/8-inch long, elliptical to oval dry fruits that have a broadly rounded base, and broad marginal winged ridges.

Distribution of giant hogweed in the United States. It has not yet been recorded in Fairfax County. It has been observed in the Washington, DC area on iNaturalist.

Sources:
King County Best Management Practices for Giant Hogweed (Heracleum mantegazzianum)
King County, 2021, Giant hogweed identification and control: Heracleum mantegazzianum - King County.

Overview:

Goutweed, also known as bishop's-weed and snow-on-the-mountain, is an herbaceous perennial plant. Goutweed is aggressive and forms dense patches, displaces native species, and greatly reduces species diversity in the ground layer. Goutweed patches inhibit the establishment of conifers and other native tree species as well. It is an ecologically versatile species. It is found in old gardens and flowerbeds, around shrubs and other plantings, and in a variety of other disturbed habitats such as felled forests, abandoned fields, and pastures. Small patches of goutweed can be eliminated by careful and persistent hand-pulling or digging up of entire plants along with underground stems (rhizomes). Pulled plants can be piled up and allowed to dry for a few days before bagging and disposing of them. Be careful to pick up all rhizomes which, if left behind, can re-root and sprout new plants. For large patches, a team of volunteers or use of herbicide is recommended

Plant Identification:

Most of goutweed’s leaves are basal, with the leafstalk attached to an underground stem, or rhizome. The leaves are divided into three groups of three leaflets, making it "triternate." The leaflets are toothed and sometimes irregularly lobed. Foliage of the "wild" type is medium green in color; a commonly planted variegated form has bluish-green leaves with creamy white edges. Sometimes reversion back to solid green or a mixture of solid green and the lighter variegated pattern occurs within a patch. Small, white, five-petaled flowers are produced in mid-summer. Flowers are arranged in flat-topped clusters (called compound umbels) and are held above the ground on a leafy stem up to about 3 feet tall. The seeds are small and elongated, similar in size and shape to carrot seeds, and ripen in late summer (though they often don’t flower in shady areas).

Patches increase in size through extension of the rhizome system. While established goutweed plants are highly competitive in shaded environments, seedlings generally need recently disturbed soil and rather bright light in order to survive. Goutweed apparently does not form a long-lived seed bank, and the seeds generally germinate the year after ripening. The primary vector for dispersal to new areas is humans. Most goutweed colonies spread to neighboring natural areas from intentional plantings, or by the dumping of yard waste that includes discarded rhizomes.

Distribution of goutweed sightings in the United States as it has not yet been recorded in Fairfax County.

EDDMapS. 2022. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online; last accessed April 18, 2022.

Observations of goutweed in the Fairfax County area on iNaturalist

Source:Garske & Schimpf, 2005

Overview:

Currently known from a few populations ranging from south of Washington, DC. to White Plains, New York. Incised Fumewort escapes cultivation, spreading by seed explosively ejected up to nine feet away. The plants form dense stands, carpeting an area within a few years and crowding out other species. Incised Fumewort is highly invasive and has the potential to become another garlic mustard, diminishing biodiversity and altering ecosystem functions. Plants should be pulled immediately using a tool to completely dig up the roots, bagged and discarded.

Plant Identification:

Plants grow 4 to 20 in. tall and have watery sap. Seedlings germinate late summer and fall, growing through the winter from pale, swollen roots about 1/2 in. long. Plants mature in spring with several stems and fibrous roots. Leaves highly divided, 2-6 in. long and wide, sharply incised. Inflorescences erect, 2-6 in. long. Flowers 10-16 per stalk, 1/2-3/4 in. long, tubular, purple with darker tips (rarely white). Fruits hanging, 1/2 in. long, green producing very small black seeds. Flowering and fruiting April to June.

EDDMapS. 2022. Early Detection & Distribution Mapping System. The University of Georgia - Center for Invasive Species and Ecosystem Health. Available online; last accessed March 29, 2022.

Source: New York Botanical Garden, ld.php (nybg.org).See Emerging Invasive: Corydalis incisa - Invasive Plants - Research Guides at New York Botanical Garden (nybg.org) for more information.

Overview:

Italian arum, also called “Lords-and-Ladies,” “Italian lily,” and “Cuckoo’s pint”, is an evergreen herbaceous ornamental plant that is showing signs of being invasive in natural areas. Italian arum occurs as individual plants in low level infestations of scattered individuals over a particular area Italian arum is poisonous, harms riparian and other sensitive habitats, and is extremely difficult to control. Spreading in yard debris and contaminated compost, it may also escape from gardens into natural areas. Ingestion of plants could cause health problems such as sickness and may require medical treatment. Contact with plant parts may cause severe skin irritation for sensitive individuals. In open areas, it can shade out small native plants and keep other plants from establishing.

Homeowners can try to dig out small infestations, taking care not to break tubers. Improper digging will only spread the plant. At minimum, cut and bag the fruit in August, before it scatters its seeds. Discard plants and tubers in plastic bags in the trash, as improper disposal spreads infestations. Do not move soil from infested sites to new areas or compost piles.

Plant Identification:

Italian arum is an ornamental groundcover which can grow up to 1.5 feet tall. Leaves emerge from tuberous roots in spring and fall, typically stay green all winter, and die back in summer. Arrowhead-shaped leaves can be all green or have cream-colored or silver-gray veins, purple splotches, or speckles. Flowers (April–June) are a yellowish unpleasant-smelling, fingerlike spadix with a pale hood, or spathe. Fruits (August–September) are orange-red and cluster tightly in oblong spikes. Thick underground tubers store much of the plant’s energy and water underground, which is why the tops regrow so easily when cut or mowed. One way the plant reproduces is by producing buds, called “daughter tubers,” which detach, and form new plants and it also spreads by seed.

Distribution of Italian arum sightings in Fairfax County.

Sources: Swearingen, J., B. Slattery, K. Reshetiloff, and S. Zwicker. 2010. Plant Invaders of Mid-Atlantic Natural Areas, 4th ed. National Park Service and U.S. Fish and Wildlife Service. Washington, DC. 168pp.

WA State Noxious Weed Control Board, ItalianArum_Brochure.pdf (wa.gov).

Overview:

Painter's pallet, also known as invasive jumpseed, is a herbaceous flowering plant native to Asia. However, because painter's pallet resembles the locally native American jumpseed (Persicaria virginiana), it has been marketed and sold as a variety of American jumpseed and is now becoming invasive in the Northern Virginia area. Because it is only now emerging as a problematic species, there is a lack of information on how it impacts ecosystems and how it ought to be managed.

Plant Identification:

Painter's pallet is an upright, clump-forming, herbaceous perennial with red stems bearing narrowly ovate, bright green leaves with a prominent, dark red to black, chevron-shaped mark in the center of each leaf. Slender, loose racemes (flower clusters) of tiny, pink or red flowers bloom from midsummer into autumn. It can reach a height of 0.7m and a spread of 0.4m after 2-5 years.

See the photos below for a comparison between the native and invasive:

Invasive

Native

Photo credit: Daniel Atha, 2021

Photo credit: Daniel Atha, 2021

Observations of Asian jumpseed in the Fairfax County area on iNaturalist. Available online; last accessed April 19, 2022.

Sources: Capital Naturalist: Painter's Palette (Persicaria filiformis) - YouTube
Persicaria virginiana var. filiformis (Virginia knotweed)

Overview:

Poison hemlock is an herbaceous, broadleaf plant growing erect from 3 to 8 feet tall. This weed prefers moist, shaded habitats subject to frequent disturbance such as those found along riparian woodlands, streambanks, and ditchbanks. Once established, it can migrate to drier upland sites. It may invade pastures, rangeland, along the perimeter of cultivated fields, and roadsides. Poison hemlock is a lethal plant with toxins mostly concentrated in the seed, lower stem, and roots.

Since poison hemlock reproduces solely via seed production, physical methods that destroy the top growth before flowering will reduce available seed. Methods that repeatedly stress and/or attack the root system are especially effective. – Repeated mowing and/or tillage in localized situations can reduce poison hemlock seed production. In wilderness or other natural areas, hand remove or cut before flowers develop; removal of the whole root is not necessary. Pile or remove debris.

CAUTION: Poison hemlock is extremely toxic to humans. When working with poison hemlock, wear Personal Protective Equipment (PPE) to limit accidental ingestion. The United States Department of Agriculture also notes that the plant can also cause some individuals to break out in a burn-like rash upon contact, so always wear protective clothing, including long pants, a long-sleeved shirt, sturdy shoes, safety glasses, and gloves when dealing with poison hemlock.

Plant Identification:

Poison hemlock is a highly toxic biennial with the musty, unpleasant odor associated with alkaloids. It grows 2 to 10 feet tall. The stems are ribbed and hollow with purplish streaks or splotches. Poison hemlock reproduces by seeds that fall near the plant and disperse via fur, birds, water, and, to a limited extent, wind. Most seeds fall from September through December, but they can fall as late as the end of February. The seeds germinate in the fall, but the plant usually does not produce flowers until the second spring. The leaves have some resemblance to ferns. They are opposite and compound, with the leaflets divided into narrow segments. When crushed, the leaves emit a rank odor. The small, white or yellowish flowers have five petals that bloom above the ovary. The flowers are born in many umbrella-shaped clusters at the end of the flower stalks. Underneath each cluster are four to six brown bracts. The fruit is egg-shaped in outline, with distinctive wavy ribs on the surface. It is composed of 2 dry halves, each with 1 seed, that eventually separate from each other. The fruit is 2-3 mm wide.

Observations of poison hemlock near the Fairfax County area on iNaturalist. Available online at Poison Hemlock (Conium maculatum), accessed May 18, 2022.

Sources: Field Guide for Managing Poison Hemlock in the Southwest, Invasive Species Western New York PRISM, Exotic Species: Poison Hemlock (U.S. National Park Service)

Overview:

Spotted knapweed is a Eurasian biennial herb which is known to invade grasslands and dry sterile, gravelly, or sandy openings such as pastures, old fields, and roadsides. It is found statewide in Virginia. Spotted knapweed shares with many other invasive species the ability to colonize disturbed areas. Once established it may infest neighboring habitats that are relatively undisturbed or in good condition. Infestation generally leads to a decline in biodiversity, because the invasive plant chokes out native vegetation. The root system of this plant does not hold soil as well as native vegetation, leading to erosion. Hand-pulling, grubbing or clipping may provide some control of light infestations. On sites where feasible, mowing or hand-cutting early in the flower stage may control spotted knapweed. This process must be repeated over several years. Plants are less likely to sprout or regrow if allowed to bolt before cutting. Although more labor intensive, hand cutting will ensure that all flower buds are destroyed.

Plant Identification:

Spotted knapweed grows in tufted clumps, one plant giving rise to 1 to 20 slender, upright stems 1 to 3 feet in height with most branching occurring in the upper half. Seedlings form a rosette of pinnately to bipinnately dissected leaves 4 to 8 in. long. Stem leaves are pinnate low on the stem, and become small, linear shaped farther up the stem. White to pink or purple flowers are at the end of the stems in thistle-like heads. Spotted knapweed seeds are spread by wind, through rivers, in crop seed and hay, and by attachment to the undercarriage of vehicles and equipment. Spotted knapweed has extremely long-lived seeds.

Observations of spotted knapweed in the Fairfax County area on iNaturalist. Available online, last accessed April 18, 2022

Sources: Invasive Alien Plant Species of Virginia, Restoration and Reclamation Review University of Minnesota, Centaurea maculosa: Invader of Western U.S. Grasslands, Watson, A., and A. Renney, 1974, Biology of Canadian weeds. Centaurea diffusa and Centaurea maculosa. Canadian Journal of Plant Science

Overview:

Yellow Archangel, commonly known as yellow archangel and yellow Lamium, is a fast-growing perennial ground cover that may be either trailing or upright depending on conditions. It spreads quickly and reduces biodiversity on the forest floor as it becomes a monoculture. Roots are not deep so plants can be hand-pulled or dug up. However, plants grow densely so hand-pulling is very labor-intensive and not very effective due the plant's ability to sprout from small fragments of root or stem, as well as its tendency to grow into and among desirable vegetation.

To fully remove, plants must be pulled up by the roots, being careful to remove all root and stem fragments. This is easiest to do fall through early spring. Sift through soil carefully to find all roots and stem fragments. Cutting alone will not control this plant. Bag and dispose in trash.

Plant Identification:

Leaves are typically variegated with silvery-grey markings and are oval-shaped and toothed. Stems are square, leaves are opposite. Leaves are hairy and coarsely toothed. Flowers are small, yellow and tubular; they grow in whorls close to stems between leaves on flowering stems that are 1 to 2 feet tall. The leaves are distinctive, non-menthol and have a somewhat unpleasant odor

Distribution of yellow archangel sightings in Fairfax County.

Sources: King County, 2020, Yellow archangel identification and control: Lamiastrum galeobdolon - King County.

Overview:

Cutleaf blackberry, or evergreen blackberry, is a thorny, thicket forming evergreen shrub in the Rose family that produces edible blackberry fruits. Cutleaf blackberry is a European species introduced for fruit production that is highly invasive and difficult to control. It forms impenetrable thickets, outcompetes native vegetation and can prevent the establishment of trees. Due to the deep roots, digging up large established plants is difficult and may need to be repeated if not all the roots are removed. Repeated cutting can keep the plants from overtaking over vegetation. Cutleaf blackberry can be controlled by digging, mowing, herbicide, plowing, and/or livestock grazing (especially goats).

Plant Identification:

Leaves are deeply incised (they look lacy as if someone has cut them up) and divided into 3-5 leaflets with toothed edges. Flowers are in clusters of 5 to 20, each with 5 petals that are white to pink. The petals have 3 lobes at the tips. The stems are stout, ridged, arching canes with sharp, stiff, curved prickles. The plant can grow 13 feet tall with stems 30 feet long. It has large, deep, woody root balls that sprout at nodes and the canes root at the tips, creating daughter plants. It closely resembles the more widespread invasive blackberry species Himalayan blackberry (Rubus bifrons or Rubus armeniacus), except for the cut-leaf shape.

Observations of cutleaf blackberry in the Fairfax County area on iNaturalist. Available online, last accessed April 18, 2022.

Source:Evergreen blackberry identification and control: Rubus laciniatus - King County

Overview:

Five-fingered (or fiveleaf) aralia, is an upright, suckering, deciduous shrub growing 8-10 feet tall with arching stems. It is typically found in forest, open forest, edge, hedgerows, and landscaped areas and is tolerant of diverse conditions. This species resprouts strongly, so cutting is not recommended.

Plant Identification:

Leaves are alternate, toothed, and palmately compound with 5 - 7 leaflets. Leaves are also 1 in. - 2.5 in. long and rich, dark green in color, though variegated forms have leaves edged in white. Leaves remain late into fall (no fall color). It has small greenish-white flowers appear in umbels in spring but are inconspicuous. Flowers on female plants (species is dioecious) may give way to small black berries if properly pollinated, but most plants sold in cultivation are females, so fruit is rarely seen. Sharp thorns appear at the stem nodes below each leaf.

Distribution of five-leaf aralia sightings in the United States as it has not yet been recorded in Fairfax County. It has been observed in the Washington, DC area on iNatuarlist.

Sources:Eleutherococcus sieboldianus 'Variegatus' - Plant Finder (missouribotanicalgarden.org; Eleutherococcus sieboldianus/NJ - Bugwoodwiki

Overview:

Holly Osmanthus, or false holly, was introduced from Japan and Taiwan as a landscaping plant. This evergreen shrub resembles true hollies, including our native American holly. It does best in acidic, moist, well-drained soil, though it tolerates a range of pH, soil types, and exposures from full sun to partial shade. For manual removal, only hand-pulling would be viable as holly osmanthus propagates from cuttings.

Plant Identification:

Holly osmanthus is a dense, upright, evergreen shrub can grow up to 15 feet tall and 10 feet wide. Its dark green, leathery, holly-like leaves bear exaggerated spines, are opposite, and are 1 to 2.5 in. long. Leaves are leathery with lustrous dark green above, yellow-green beneath with reticulate venation. The margin is entire (not serrated) or may have one to four large spine-tipped teeth on each side, resembling a holly leaf. Clusters of small, white, fragrant flowers appear in early to mid-fall, followed by blue-black- fruit. If both male and female plants are present the seed produced is viable.

Distribution of holly osmanthus sightings in Fairfax County.

Sources:
Plant Invaders in the District of Columbia; Brookman, 2015 (Bugwoodwiki)

Overview:

Various species in the Photinia genus are emerging as invasive species. They are popular ornamental shrubs (or small trees) in the rose family. Several examples of Photinia spp. which could threaten biodiversity in the Fairfax County area can be found below. The Lower Hudson PRISM offers the following advice for control of Photinia villosa, which might be transferable to other species of the same genus [see Photinia villosa | Lower Hudson Partnership for Regional Invasive Species Management. (lhprism.org)]: Pulling can attain some measure of control but root sprouting is possible with larger individuals. This method is better used with seedlings or very small plants. Waste material can be burned, chipped or composted so long as management was completed prior to seed set. Any fruit must be bagged and disposed of. All roots must be thoroughly dried and or crushed. See the same source for information on chemical control options.

Plant Identification:

Because Photinia spp. have recently emerged as species of concern, there is little information about which specific species are likely to be problematic. Therefore, the following may not be a comprehensive list of all possible EDRR Photinia species.

Oriental photinia (Photinia villosa): An attractive member of the rose family, Oriental photinia is a deciduous shrub or small tree, growing up to 15 feet tall given the right conditions. Eye catching in all seasons, this species produces clusters of creamy white flowers in spring, bright orange-red foliage in fall, and red berries in mid-winter, hence the species’ common name, Christmas berry. Leaves are simple, alternately arranged, approximately 3 in. long with serrate, gland-tipped margins. Leaves are shiny, bright green above and hairy below. Flowers are Creamy white to occasionally pinkish flowers approximately ⅓ inch across appear in May and June in the Hudson Valley, occurring in terminal clusters. Flowers develop into clusters of round red, juicy pomes, ripening and appearing most conspicuous in mid-winter. It is often found at the edges of forest fragments and in forest clearings, where birds may deposit the seeds. Mature plants of Oriental photinia produce ample fruit each season, with 3-4 seeds in each pome. Fruits persist on the plant well into winter and can be dispersed long distances by frugivorous birds. Vectors include birds and small mammals. A tenacious shrub capable of producing copious amounts of bird-dispersed seed each year, Oriental photinia spreads rapidly and easily into new habitats. This species may form thickets, homogenizing the shrub layer, displacing native species, and shading out germinating seedlings with its dense canopy

Observations of P. villosa in the Fairfax County area on iNaturalist. Available online.

Source:
Photinia villosa | Lower Hudson Partnership for Regional Invasive Species Management. (lhprism.org)].

Red tip (Photinea x fraseri): Red tip, also called red top or chokeberry, is a traditional hedge shrub in the American South. It has distinctive foliage that is bright red when young. As it matures, it passes through shades of reddish-copper eventually maturing to a rich dark green. The glossy leaves are finely serrated and arranged alternately on the stem. They are 3 in. to 5.5 in. long and 1.5-2 in. wide. The shrub typically grows 10-12 ft. in height but may reach 15 ft. when well established. Small white flowers appear in spring arranged in flat-domed, 5-7 in. diameter clusters. Red tip is a hybrid cross of Chinese native, Photinia serratifolia (or Photinia serrulata) and the Japanese native, Photinia glabra. This species spreads into shaded woodlands and creek sides.

Distribution of Photinea x fraseri sightings in the United States as it has not yet been recorded in Fairfax County.

Observations of Photinea x fraseri in the Fairfax County area on iNaturalist. Available online.

Source:
Texas Invasives

Taiwanese photinia

(Photinia serratifolia (syn. Photinia serrulata)): Taiwanese photinia or Chinese photinia is a flowering shrub or tree in the flowering plants family Rosaceae, found in mixed forests of China, Taiwan, Japan, the Philippines, Indonesia, and India. The tree is evergreen, with white flowers emerging in spring accompanied by red-colored leaves, and red fruits growing in autumn. It grows typically 13–20 ft., sometimes up to 39 ft., tall. Its leaves are toxic due to the presence of cyanogenic glycosides. The flower, blossoming in spring, typically lasts for 1 to 2 weeks. The flower has bell-shaped sepal split into five lobes, and around 20 stamens. Ovaries contain two to four locules, with one ovule in each locule. The tree produces high amount of bright, red colored fruits that are small pomes with diameters ranging from 0.16–0.47 in., each containing 1 to 4 seeds. The fruit ripen in autumn and survives through winter, is a food source to various kinds of birds, including thrushes, waxwings, and starlings. The seeds spread primarily through bird excretions.

Distribution of P. serratifolia sightings in the United States as it has not yet been recorded in Fairfax County. It was identified near Arlington, VA on iNaturalist

Source:
Chinese Photinia (Photinia serratifolia) (inaturalist.org) , citing Wikipedia].

Overview:

Leatherleaf mahonia is native to China. It has been planted as an ornamental and is invading woodlands in the southeastern and mid-Atlantic states. It is an evergreen shrub that grows 5-10 ft. tall. Remove prior plantings, and control sprouts and seedlings. Bag and dispose of fruit in a dumpster or burn. New plants can be pulled.

Plant Identification:

The unusual leaves are pinnately compound, about 18 in. long with 9-13 paired, glossy holly-like leaflets. The leaflet margins have 2-7 teeth per side that are about ¼ in. or less in length. Leaflets are very thick and stiff. Flowering occurs in early spring. Fragrant yellow flowers emerge from the tips of the plant in attractive spike-like sprigs. The fruits are green berries that turn bluish black with a grayish bloom. Fruits hang in grapelike clusters.

Distribution of Leatherleaf mahonia sightings in Fairfax County.

Sources:
Leatherleaf_Mahonia.pdf (bugwoodcloud.org)
Swearingen, J., B. Slattery, K. Reshetiloff, and S. Zwicker. 2010. Plant Invaders of Mid-Atlantic Natural Areas, 4th ed. National Park Service and U.S. Fish and Wildlife Service. Washington, DC. 168pp.

Overview:

Jetbead is a multi-stemmed deciduous shrub that was introduced from Central China, Korea and Japan in 1866 for ornamental purposes. Found in at least 17 states east of the Mississippi, it has recently come to the attention of land managers who noticed it becoming invasive in natural habitats away from intentional plantings. It is very shade tolerant and can do well in forest edges and interiors. Once established, it shades out native plants in the ground layer and inhibits native tree generation. Jetbead invades forests, creating a thick shrub layer that displaces native shrubs, shades out understory species and restricts tree seedling establishment. Jetbead spreads by seed and by vegetative means.

Plant Identification:

Jetbead typically grows to a height of 6 ft. and a width of 7 ft. Its leaves are opposite, simple, bright green in color and 2.5 - 4 in. long. Leaf margins are doubly toothed with a rough appearance, and it has ribbed veins with a long, pointed tip. Leaves persist into fall and have an obvious lime green color. Jetbead’s flowers occur in terminal clusters and have four white, large petals and 4 large, toothed sepals. They bloom in April through early June. Fruits grow in clusters of four black bead-like fruits. Fruits have single seeds and immature fruits are dark, reddish orange. They appear in midsummer and ripen in September – December.

Distribution of jetbead sightings in Fairfax County

Sources: Brookman, 2014, Rhodotypos scandens/NJ - Bugwoodwiki)
Swearingen, J., B. Slattery, K. Reshetiloff, and S. Zwicker. 2010. Plant Invaders of Mid-Atlantic Natural Areas, 4th ed. National Park Service and U.S. Fish and Wildlife Service. Washington, DC. 168pp.

Overview:

Amur corktree is a popular ornamental shade tree (male clones) that was introduced intentionally into the USA in 1865. In North America, it has been found invading forest edges, canopy gaps, and areas of human disturbance, but can also persist in the understory of closed-canopy forests. Amur corktrees can suppress regeneration of native tree species and displaces native shrub and herbaceous layers. Control should prioritize the removal of female (fruiting) trees first. Trees can be controlled by girdling. Resprouts vigorously if not treated after cutting. Follow up with the replanting of desirable species.

Plant Identification:

Amur corktree is a deciduous tree that typically grows 30-50 ft. tall from a shallow, but wide-spreading root system. Trees have short, straight trunks that divide into numerous spreading branches to form a rounded but wide canopy.

Outer bark is grayish-brown, soft, and corky, becoming more rough-textured and furrowed with age. Inner bark is bright yellow. Leaves are opposite and divided into 5-13 leaflets that are 2.5-5 ft. long. Leaflets are lance-shaped to elliptical and have very slightly toothed margins that often appear smooth from a distance. Leaves are bright green throughout summer and turn yellow in autumn. Flowers are yellow-green (sometimes maroon), non-showy, less than 0.12 in. in diameter, and appear in loose clusters among leaves in late spring to early summer. Fruits are spherical, 0.4 in. across, berry-like, and green, turning black at maturity. Fruits remain on the tree through early winter. Crushed foliage and fruits are odorous, variously described as turpentine-like, skunk-like, or citrusy. Individuals are long-lived under some conditions. The tree spreads by seed which remain viable for several years.

Distribution of Amur corktree sightings in Fairfax County.

Sources: Amur cork tree | (Phellodendron amurense) | Wisconsin DNR).
Rawlins et al., 2018, New Invaders of the Northeast and Northcentral United States (bugwoodcloud.org).

Overview:

Castor aralia, also known as prickly castor-oil tree and tree aralia, is a deciduous tree which typically grows 40-60 ft. tall. Castor aralia prefers cool, moist climates and is very cold tolerant. It can be found escaping landscaping and invading field and forest margins. This tree resprouts easily, so herbicide treatment, as opposed to cutting, is recommended.

Plant Identification:

Castor aralia trees grow from a shallow, fleshy root system that may occasionally send up root sprouts. There is often one main trunk that branches to form an upright, oval canopy. Young bark is armed with long, thick spines; mature bark is generally spine-less, grayish-brown, and deeply furrowed. Leaves are 7-12 ft. across, alternate, and attached to the branch with long petioles. Leaves, typically with 5-7 lobes, are shaped like the palm of a hand. Lobes may be shallow, or deeply divided nearly to the leaf base. Lobe margins are finely toothed. Leaves are a dark glossy green initially, turning dull yellow to red in fall. Flowers appear profusely in large clusters of umbels at stem branches in late summer. Each flower is tiny with 4-5 creamy white petals. The tiny, berry-like fruits occur in ball-like clusters and are black at maturity. Trees generally live over 40 years and can spread by seed and sprouting from the root system. Though the seeds are considered short-lived, some remain viable for at least two years.

Distribution of Castor aralia sightings in Fairfax County.

Sources: Brookman, 2014, Kalopanax septemlobus/NJ - Bugwoodwiki.
Rawlins et al., 2018, New Invaders of the Northeast and Northcentral United States (bugwoodcloud.org) See the source listed above for more information on species look-alikes.

Overview:

Japanese angelica tree, or Japanese aralia is a deciduous tree or shrub which can grow to 40 ft. tall. It is colonial and thicket forming and grows in irregular form and is multi or single stemmed. Japanese angelica tree is highly threatening to native plant communities and should be controlled; however, it resprouts strongly so herbicide treatment, as opposed to cutting, is recommended.

Plant Identification:

Leaves are alternate and 2 or 3 times pinnately compound. They are toothed or nearly toothless with downy hairs below. Leaflet size is variable and ranges from 2 in. - 4.7 in. long, whereas the large, entire leaf can be 2 - 4 feet long. Leaves turn yellow to reddish purple in fall. Japanese angelica tree has spines at leaf axils and its main leaf veins extend to leaf edge. Its leaflets typically have sessile or very short petioles (stem). Its flowers are whitish to cream colored, borne in large, inflorescence 12 in. – 24 in. long. Flowers are in clusters and are multi-stemmed and lack a central axis. They are often wider than tall, with flower base surrounded or over topped by foliage. Flowers bloom in late July – August. Fruits are small purple to black berries which occur in circular formations. Fruits appear in August – September and ripen by October

Distribution of Japanese angelica tree sightings in Fairfax County.

Sources: Susan Brookman, 2014, Aralia elata/NJ - Bugwoodwiki. Mistaken Identity? Invasive Plants and their Native Look-alike

Overview:

Japanese Pagoda tree is a fast-growing deciduous tree that will reach a height and width of about 30-60 ft. The pagoda tree is capable of growing in all soil types, although it grows best in well drained, loamy soils and in full sun conditions. It is resistant to pests, drought, and pollution. Young trees may be cut and the roots dug out.

Plant Identification:

The tree is deciduous and characterized by having alternate branching with leaves pinnately compound, usually with 6 pairs of petiolate, entire leaflets. It produces white flowers in late summer (usually August) and has mature fruits in late autumn (usually November). The flowers are self-fertilizing with both pistils and stamens, with 5 pappillonaceous (butterfly-like) petals 0.1-0.2 in. long. They are arranged in terminal panicles with 10 stamens, an elongate pistil and superior ovary. Fruits of the Pagoda Tree are hanging pod-like legumes 1.1-3.1 in. long. They are a fleshy and yellow to green when young and reddish-brown when mature. There are 2- 9 seeds within each pod.

Distribution of Japanese Pagoda tree sightings in the Fairfax County area on iNaturalist. Available online.

Source: Jocelyn Karsk (National Park Service), 2012, Styphnolobium_japonicum2012NCREPMT-1.pdf (bugwoodcloud.org).

Overview:

Bushkiller is a perennial herbaceous vine in the grape family (Vitaceae) that will climb up trees and other supports. Bushkiller tends to invade in disturbed areas such as fallow fields, residential areas, overgrazed pastures and harvested forests. It will also grow in flood plains. This fast-growing vine will climb existing native plants and either stress the plant by breaking branches due to its weight or block the sunlight for native plants. It can also act as a “ladder” in forest fires, letting the fire climb higher than normal, causing more damage.

This plant can be hand-pulled, but all root material must be removed for the treatment to be successful. Bushkiller can re-sprout from any rhizome left in the soil. Removed vegetation should not be composted, as it can also re-sprout from buried stems. Application of heavy mulch to plants that have not started climbing will result in dormancy, but the plant may re-sprout the following year.

Plant Identification:

This vine has five leaflets per leaf, with the middle leaflet on its own stem. Leaves can be up to 3 in. wide and 3 in. long, and usually no smaller than 1/2 in. wide and 1 in. long. The leaflets are ovate with dentate margins, with silvery-white coloration on the lower surface. Clusters of white, red and yellow flowers appear in the late summer and produce round, grape-like berries with 2-4 seeds. It can reproduce by seed or rhizome, but seeds are less likely to be viable the further north the plant is found. Bushkiller could be confused with Virginia creeper (Parthenocissus quinquefolia), as both plants have five leaflets, but the middle leaflet on Virginia creeper does not contain its own stem

Distribution of bushkiller sightings in the United States as it has not yet been recorded in Fairfax County. However, according to iNaturalist, observations have been made in Washington, DC and Arlington, VA

Source: Koepke-Hill & Armel, 2009, Bushkiller (tennessee.edu)

Overview:

Kudzu is a climbing perennial vine in the pea family. Kudzu grows well under a wide range of conditions and in many soil types. Preferred habitats are open, sunny areas like forest edges, abandoned fields, roadsides and disturbed areas. Its vigorous growth and large leaves smother and shade out native plants. It can kill trees through girdling and the extra weight of vines can lead to toppling during storms.

For successful long-term control of kudzu, the extensive root system must be destroyed. Any remaining root crowns can lead to reinfestation of an area. Mechanical methods include repeated cutting of vines just above ground level, frequent mowing and herbicide treatment.

Plant Identification:

Kudzu vines may extend 32-100 ft. in length, with stems up to 4 in. in diameter. Its roots are fleshy, with massive tap roots that can get to 7 in. or more in diameter, 6 ft. or more in length, and weigh as much as 400 lbs. Up to 30 vines may grow from a single plant. Kudzu’s leaves are alternate, deciduous, and compound, with three broad leaflets up to 4 in. across, leaflets may be entire or lobed with hairy margins. Kudzu has individual flowers, about ½ in. long, which are purple, fragrant and borne in upright clusters during late summer. Fruits are brown, hairy, flattened seed pods, each of which may contain as many as ten hard seeds. It expands locally by vegetative means through runners and rhizomes and by vines that root at the nodes to form new plants. It may spread by seed in areas where a pollinator, the giant resin bee, occurs. Thick tangles of various vines including grape, porcelain berry and bittersweet may be mistaken for kudzu, as well as some native three-leaved vines in the pea family.

Distribution of kudzu sightings in Fairfax County.

Source: Swearingen, J., B. Slattery, K. Reshetiloff, and S. Zwicker. 2010. Plant Invaders of Mid-Atlantic Natural Areas, 4th ed. National Park Service and U.S. Fish and Wildlife Service. Washington, DC. 168pp.