Invasive Plants

Invasions by non-native species are a significant threat to our forests, causing environmental degradation and expensive eradication efforts. Invasive plants out-compete and replace native species, resulting in decreased ecosystem diversity and stability, with less food, shelter and habitat for wildlife.

Invasions by non-native species are a significant threat to our forests, causing environmental degradation and expensive eradication efforts. Invasive plants out-compete and replace native species, resulting in decreased ecosystem diversity and stability, with less food, shelter and habitat for wildlife.

Many forests and other areas within the Conservancy are plagued by non-native invasive plants – many of which were introduced by the nursery trade. Awareness among homeowners regarding the identification and home use of invasive plants is critical to reduce their introduction and spread into natural open space.

Check out our tips on Gardening with Virginia Natives to avoid planting and spreading invasives!
 
The Virginia Department of Conservation and Recreation (DCR) ranks invasive plants based on their ability to alter ecosystems, ability to invade, and difficulty of removal.  The following are present in Conservancy forests.

Highly Invasive

Tree-of-heaven (Ailanthus altissima) – is a tree which seeds prolifically and readily sprouts from stumps and roots, with a rapid growth rate. Tree-of-heaven is allelopathic, meaning that it can produce toxic substances that inhibit the growth of nearby plants.

Garlic mustard (Alliaria petiolata) – is a 2-4 foot upright herbaceous bi-annual that occurs under forest canopies. It spreads by seeds which can lie dormant for 2-6 years. It is also allelopathic, emitting chemicals to kill surrounding plants and microbes.

Oriental bittersweet (Celastrus orbiculatus) – is a deciduous, woody vine that occurs in forests, along roadsides and in disturbed areas. The climbing vine grow in thick stands that strangle other vegetation and can weaken trees by weighing down limbs.

Canada thistle (Cirsium arvense) – is an herbaceous perennial growing up to 5 feet high. It reproduces via seeds and a prolific root system. It is allelopathic, meaning that it can produce toxic substances that inhibit the growth of nearby plants.

Autumn olive (Eleagnus umbelata) – is a drought-tolerant shrub which spreads readily, forming dense stands. It is found on the forest edge and in open fields.

Chinese privet (Ligustrum sinense) – is a shrub which spreads readily and can grow up to 12 feet high. It prefers damp areas including bottomlands and stream banks.

Japanese honeysuckle (Lonicera japonica) – takes both vine and herbaceous growth forms, and rapidly spreads throughout forests, girdling and killing trees and shrubs. Various other shrub forms exist (Lonicera spp.).

Japanese stilt grass (Microstegium vimineum) – is a sprawling annual grass, usually found in forests. It primarily spreads on trails and recreational areas by seeds hitchhiking on visitor’s shoes and clothes. Due to prolific seeding, removal can take over 5 years.

Wavyleaf basketgrass (Oplismenus hirtellus ssp. undulatifolius) – is a perennial, rapidly-spreading grass. Shade tolerant, it thrives in wooded areas. Its sticky seeds travel easily on mammals and clothing.

Mile a minute (Polygonum perfoliatum) – is a climbing, annual vine that occurs in damp, sunny areas. It can grow rapidly, up to half a foot per day, choking out native vegetation.

Multiflora rose (Rosa multiflora) – is an evergreen shrub with heavy thorns and small, fragrant, white flowers. It colonizes by prolific sprouting and rooting of stems, and spreads by animal dispersal of seeds. Multiflora Rose has been widely planted along fence rows and right-of-ways.

Japanese wineberry (Rubus phoenicolasius) – is a deciduous shrub that grows in a wide variety of habitats from disturbed areas to mature forests. It can grow up to 9 feet high and often grows in dense stands.

Medium Invasive Ranking

Small carpetgrass (Arthraxon hispidus) – is a grass that grows up to 18” tall and spreads through seeds that can be dispersed by flowing water. It forms dense stands, particularly along shorelines, threatening native vegetation.

Japanese barberry (Berberis thunbergii) – is a shade tolerant, drought resistant, adaptable shrub. It forms dense stands, shading out native plants while altering soil pH, nitrogen levels and biological activity in the soil. It spreads by seed, transported by birds and small mammals, and though horizontal branches that root freely when they touch ground.

Bull thistle (Cirsium vulgare) – is a biennial that spreads by seed.

Royal paulownia (Paulownia tomentosa) – is an extremely fast-growing tree that spreads by seed and competes with native species in disturbed natural areas including forests, stream banks and steep rocky slopes. It tolerates high soil acidity, drought and low soil fertility enabling it to grow and reproduce on harsh, exposed sites.

Willowsford Conservancy

44095 Pipeline Plaza, Ashburn, VA 20147

Phone: 571-252-3980

info@willowsfordconservancy.org

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Willowsford Farm Stand

23595 Founders Drive, Ashburn, VA 20148

Phone: 571-297-6900

farm@willowsfordfarm.com

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