General: Common Comfrey is a perennial herb.
Flowers: Funnel-shaped with 5 shallow but distinct lobes that fuse together at the base. Flowers grow in bractless, drooping clusters with several to many small flowers. Flowers can be cream or dull blue to purple and are 1.5 cm – 1.8 cm long.
Stems: Covered in small, bristly hairs and grow 0.5 m – 1.2 m tall.
Leaves: Basal, large, and alternating on the lower stem. They are either egg-shaped or oblong, 15 cm – 30 cm long and 7 cm – 12 cm wide. Leaves become smaller higher up the stem and are arranged opposite of each other.
Fruit: A cluster of 4 nutlets that turn a shiny brown-black when they mature.
Roots: Branched taproot.
Prickly or Rough Comfrey (Symphytum asperum) is a fleshy rooted perennial that is 0.6 m – 2 m tall, with a rough, hairy stem, and leaves that are narrow, stalked and alternate. The flowers are funnel-shaped and pink, later changing to sky blue and bloom from June to August. Prickly Comfrey can be found growing in inhabited areas, parks, gardens, and coastlines.
Habitat and Origin
Common Comfrey originates from Europe and parts of Asia, where it is used as a garden ornamental and a medicinal herb. It is still used today to treat skin irritations, cuts, sprains, and swelling; however, it is carcinogenic when ingested.
Common Comfrey can be found growing in shady areas such as meadows and woods, especially near streams and rivers. It grows best in nutrient-rich soils, but can also be found growing in disturbed areas.
Propagation & Vectors of Spread
Common Comfrey reproduces mainly vegetatively, growing new plants from root fragments. It can also reproduce by seed, though it may take up to 2 years for plants to begin growing.
Common Comfrey is spread when mowed or cut as root fragments grow into new plants. It is also spread through seeding. Seeds can be transported by wind, water, humans, and animals. Additionally, it is spread through nursery sales as it is used as a garden ornamental and for medicinal purposes.
Ecological and Health Impacts
- Outcompetes native plant species.
- Mines nutrients out of the soil, making them unavailable for other species.
- Hairs on stems can cause skin irritation.
- Contains toxic properties that can lead to liver damage and in some cases, death.
What Can I Do?
Common Comfrey is currently found throughout the Sea to Sky Corridor, so the best approach to controlling its spread is by PREVENTION.
Learn to identify Common Comfrey: use the images presented in this profile page to learn how to identify Common Comfrey.
What to do if you spot it: You can report any Common Comfrey sightings by clicking here.
- Regularly monitor properties for weed infestations.
- Ensure soil and gravel are uncontaminated before transport.
- Check wildflower mixes to ensure that they do not contain Common Comfrey.
- Minimize soil disturbances (e.g. use grazing plans that prevent soil exposure from overgrazing), and use seed mixes with dense, early colonization (e.g. alfalfa or barely) to re-vegetate exposed soil and resist invasion.
- Ensure that plants are disposed of in a garbage bag if found in floral arrangements to prevent seeds from spreading.
- 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 Common Comfrey in a garden, no matter how well-contained its enclosure may seem.
- Move soil that has been contaminated with Common Comfrey.
- Once established, Common Comfrey can be very difficult to remove due to its large taproot.
- If digging out, ensure that as much of the taproot is removed as possible, because new plants will form from any fragments left behind.
- Removing during hot, dry weather will aid in killing off remaining root fragments.
- Broadleaf herbicides provide optimal control, and as the plant grows, a higher rate of herbicide is necessary.
- Using a surfactant will increase coverage and ensure that herbicide penetrates the plant, as hairy bristles on the stem make it difficult.
- 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.
Planting competitive, native plants in areas where Common Comfrey has been removed will help to prevent weed occurrence.
eFlora, Common Comfrey, http://linnet.geog.ubc.ca/Atlas/Atlas.aspx?sciname=Symphytum%20officinale
Invasive Plant Atlas of the United States, Common Comfrey, https://www.invasiveplantatlas.org/subject.html?sub=13086
Minnesota Wildflowers, Common Comfrey, https://www.minnesotawildflowers.info/flower/common-comfrey
Missouri Botanical Garden, Symphytum offcinale, http://www.missouribotanicalgarden.org/PlantFinder/PlantFinderDetails.aspx?kempercode=b472
Nature Gate, Prickly Comfrey, http://www.luontoportti.com/suomi/en/kukkakasvit/prickly-comfrey
Peace River Regional District, Profile of Invasive Plant Species Within the Peace River Regional District, https://prrd.bc.ca/wp-content/uploads/page/plans-reports-invasive-plants/PRRD-Invasive-Plant-List-and-Decriptions.pdf