Other common names:
- Dog Burr
- Gypsy Flower
- Rats and Mice
General: Hound’s-tongue is a noxious biennial or short-lived perennial plant that produces a rosette during its first year of growth and flowers and seeds during its second year of growth. It belongs to the Boraginaceae (Borage) family.
Flowers: Plants have several narrow flower clusters that are slightly coiled. Flowers are dull reddish-purple, drooping slightly along slender stalks, and consist of 5 petals each.
Stems: First-year plants form a rosette and bolt the following year, reaching up to 1.5 m tall with stout, upright stems. Stems are covered in hair and often branched in the upper portion.
Leaves: Rosette leaves are up to 30 cm long and dog tongue-shaped, with broad tips that taper at the base. Stem leaves are reduced, alternate, and stalkless, with smooth edges and distinctive veins. Mature plants develop rough, hairy leaves.
Seeds: Seeds are brown to grayish-brown and have a rounded-triangular shape. They are covered with short, hooked bristles and cling to clothing and fur like velcro.
Roots: Plants have a thick, black, woody taproot.
Common Comfrey (Symphytum officinale) is found throughout the Sea to Sky. Unlike Hound’s-tongue, Common Comfrey has smooth seeds and long, funnel-shaped flowers. To add, it generally has wider leaves and narrower sepals.
Habitat and Origin
Hound’s-tongue is native to Eurasia and was introduced to North America as a seed contaminant.
The plant is shade-tolerant and typically requires more than 30 cm of rain annually. It prefers forest sites and thrives in forest openings cleared by logging operations and road construction. It is also common to find Hound’s-tongue in pastures, along roadsides, abandoned fields, and disturbed habitats.
Propagation & Vectors of Spread
Hound’s-tongue is a biennial; in its first year, it forms a rosette which then will bolt and go to seed the following second year. Plants reproduce by seed and can produce up to 2,000 barbed seeds per year. Seeds are viable for up to one year when they are buried in the soil and up to three years on the surface.
Velcro-like seeds attach to the fur of animals and other carriers such as clothing, machinery, and vehicles. Over-grazing and disturbance further encourage the spread and growth of Hound’s-tongue.
Ecological, Economic, & Health Impacts
- Contains toxic pyrrolizidine alkaloids, which inhibit liver cells from reproducing, poisoning wildlife if ingested.
- Poisonous to livestock, particularly horses & cattle, if ingested.
- Bur-like seeds cling to the fur of livestock and can become embedded in the eye or eyelids, potentially causing eye damage.
- Bur-like seeds can impact recreational activities.
- Infestations in hay fields reduce available forage.
What Can I Do?
Hound’s-tongue is not yet found in the Sea to Sky, so PREVENTION is key:
Learn to identify Hound’s-tongue: use the images presented on this profile page to learn how to identify Hound’s-tongue.
What to do if you spot it: You can report any Hound’s-tongue sighting by clicking here.
- Regularly monitor properties for weed infestations.
- Minimize soil disturbances and promptly revegetate disturbed areas to prevent the growth of Hound’s-tongue.
- Check wildflower mixes to ensure that they do not contain Hound’s-tongue.
- 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 Hound’s-tongue in a garden, no matter how well-contained its enclosure may seem.
- Compost any flowering heads or buds. Instead, dispose of Blueweed 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 Hound’s-tongue.
- Hand pull or dig up isolated plants and small patches and remove as much of the taproot as possible.
- Cutting second-year plants reduce seed production and spread.
- If plants are cut close to the ground, many plants will not re-grow.
- Monitor and repeat mechanical control as necessary.
- Seed the controlled area with competitive native species.
- Metsulfuron is effective any time the plant is actively growing.
- First-year rosettes can be controlled with 2,4-D, however, this herbicide is fairly ineffective on second-year plants.
- 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.
- Some biological agents exist, including a flea beetle (Longitarsus quadriguttatus) and a weevil (Mongulones crucifer).
- Fraser Valley Invasive Species Society, Hound’s Tongue, https://fviss.ca/invasive-plant/hounds-tongue
- Government of BC, Ministry of Forests. Hound’s Tongue https://testwww.for.gov.bc.ca/hfp/noxious/plants/hounds-tongue.htm
- Invasive Species Council of BC, Hound’s Tongue, https://bcinvasives.ca/invasives/hounds-tongue/
- King County, Houndstongue, https://your.kingcounty.gov/dnrp/library/water-and-land/weeds/Brochures/Houndstongue_factsheet.pdf
- Lillooet Regional Invasive Species Society, Hound’s Tongue (Cynoglossum officinale L.), https://lriss.ca/species/hounds-tongue-cynoglossum-officinale#accordion_panel_6/
- National Invasive Species Information Center, Houndstongue, https://www.invasivespeciesinfo.gov/terrestrial/plants/houndstongue
- Okanagan Invasive Species Online, Hound’s-Tongue, Https://www.oiso.ca/wp-content/uploads/FACTSHEET_HT_May-2015.pdf
- Washington State Noxious Weed Control Board, Houndstongue, https://www.nwcb.wa.gov/weeds/houndstongue