- Tall Whitetop
- Virginia Pepperweed
- Broadleaved Peppergrass
- Broad-leaved Pepperweed
General: Perennial Pepperweed is a herbaceous perennial in the Mustard family (Brassicaceae).
Flowers: White, four-petal flowers that form dense clusters at the end of branches.
Stems: Are branched, erect, waxy and grey-green, occasionally with red spots. Stems can grow up to 2 m tall and are woody at the base.
Leaves: Rosette leaves are oval or oblong with smooth or jagged edges. Stem leaves attach directly to the base of the plant in an alternate arrangement, and are lance-shaped with smooth to toothed margins. Leaves become smaller towards the top of the stem.
Seeds: Are small, flat and round or oval-shaped. Each seed pod contains two seeds.
Roots: Are deep, minimally branched, and enlarged at the soil surface, forming a semi-woody grown.
Similar Invasive Species
Hoary Cress (Lepidium draba) is considerably shorter than Perennial Pepperweed, and its upper leaves clasp the stem.
Baby’s Breath (Gypsophila paniculata) flowers can also be confused with Perennial Pepperweed. However, Baby’s Breath is much shorter (up to 1 m tall) and its leaves are much narrower.
Similar Native Species
Pearly Everlasting (Anaphalis margaritacea) is shorter than Perennial Pepperweed. Its leaves are also narrower and give off a grey hue due to the fine hairs that cover the leaves and stems.
Habitat and Origin
Perennial Pepperweed is native to southeastern Europe and southwestern Asia. It is believed to have been introduced to North America mixed into a shipment of sugar beet seeds.
The plant tolerates a variety of soil characteristics, such as clayey, loamy, sandy or silty. It is also tolerant of soils that contain high levels of calcium. Perennial Pepperweed invades flood plains, irrigation structures, pastures, wetlands, riparian areas, roadsides, dry hillsides and residential sites.
Propagation & Vectors of Spread
Perennial Pepperweed reproduces primarily vegetatively; its rhizomes can grow up to 3 m annually and new plants can form from root fragments. Reproduction by seeds is possible as well.
Local dispersal occurs predominately through the creeping rhizome system. However, Perennial Pepperweed can spread through its seeds which can be transported in water or by attaching themselves to farm equipment, livestock and wildlife.
Long-distance dispersal occurs by contaminated seeds and hay mixes, the horticulture industry, and vehicles.
Ecological, Economic, & Health Impacts
- Decreases native biodiversity by creating a monoculture.
- Increases soil salinity.
- Decreases availability of suitable nesting habitats.
- Reduces forage quality and makes horses and cattle sick by preventing sodium and water retention.
What Can I Do?
Perennial Pepperweed is currently not yet found in the Sea to Sky region, so PREVENTION is key:
Learn to identify Perennial Pepperweed: use the images presented in this profile page to learn how to identify Perennial Pepperweed
What to do if you spot it: You can report any Blueweed sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Minimize soil disturbances and promptly revegetate disturbed areas to prevent the growth of Perennial Pepperweed.
- Check wildflower mixes to ensure that they do not contain Perennial Pepperweed.
- Ensure all flowering heads or buds are bagged or covered to prevent spread during transport to designated disposal sites.
- Unload, park or store equipment or vehicles in infested areas; remove plant material from any equipment, vehicles or clothing used in such areas and wash equipment and vehicles at designated cleaning sites before leaving infested areas.
- Plant Perennial Pepperweed in a garden, no matter how well-contained its enclosure may seem.
- Compost any flowering heads or buds. Instead, dispose of Perennial Pepperweed in the general/household waste stream at the landfill as the seeds will be able to persist the composting process.
- Move soil, gravel, or fill that has been contaminated with Perennial Pepperweed.
Seedlings can be controlled by hand-pulling or tillage; however, these techniques, along with mowing, do not control established plants because shoots quickly re-sprout from the vast root reserves.
Chlorsulfuron, 2,4-D and glyphosate have proven effective to treat Perennial Pepperweed, but repeat applications over several years are often necessary.
We recommend that any herbicide application is carried out by a person holding a valid BC Pesticide Applicator Certificate. Before selecting and applying herbicides, you must review and follow herbicide labels and application rates; municipal, regional, provincial and federal laws and regulations; species-specific treatment recommendations, and site-specific goals and objectives.
There is no biocontrol available for this plant.
Establishing and maintaining competitive perennial vegetation can dramatically slow the spread of Perennial Pepperweed. In ornamental plantings, closely planted perennials, shade trees and plastic mulches can also prevent the spread of Perennial Pepperweed.
- Caribou Regional District, Perennial Pepperweed, https://www.cariboord.ca/en/home-and-property/perennial-pepperweed.aspx#Habitat-Impacts
- Fraser Valley Invasive Species Society, Perennial pepperweed, https://fviss.ca/invasive-plant/perennial-pepperweed
- Government of Canada, Invasive Species Alert: Perennial Pepperweed, https://www2.gov.bc.ca/assets/gov/environment/plants-animals-and-ecosystems/invasive-species/alerts/perennial_pepperweed_alert.pdf
- Invasive Plant Atlas of United States, Perennial pepperweed, https://www.invasiveplantatlas.org/subject.html?sub=5931
- Invasive Species Council of BC, Perennial Pepperweed TIPS Factsheet, https://bcinvasives.ca/wp-content/uploads/2021/01/Perennial_Pepperweed_FS.pdf
- University of California Agriculture & Natural Resources, Perennial Pepperweed, http://ipm.ucanr.edu/PMG/PESTNOTES/pn74121.html