Hound’s-tongue

Identification & Biology
Latin Name : Cynoglossum officinale
Category : Terrestrial Plants
Description :
  • Tap-rooted biennial • Grows from 0.5 to 1.2 metres tall
  • Bottom leaves are large and hairy (10-30 cm long, 2-5 cm wide)
  • Stem leaves are short and stalkless
  • Dull reddish-purple flowers produce four nutlets (seeds) each
  • Seeds are brown to grayish-brown, rounded triangular in shape and are covered with short, hooked prickles.

Hound’s-tongue seeds germinate in the spring producing large tufts of tongue shaped leaves. These rosettes then bolt and flower in the second (and possibly subsequent) year, producing as much as 2,000-4,000 seeds per plant. These seeds readily spread by sticking to the hair, wool and fur of animals, as well as human clothing. Flowers bloom from May through July with each flower head yielding four nutlets, which then mature into the burred seeds. Seeds that remain attached to the parent plant may remain viable for 2-3 years. Hound’s tongue rosettes can withstand considerable drought stress. The plant’s thick deep taproot can exploit lower sources of ground water and nutrients, enabling the plant to survive water deficits and to delay flowering until conditions are favorable. The root also serves as a food reserve which is protected underground.

Habitat

In British Columbia, hound’s-tongue grows from low-mid elevation forests. It is associated with soil disturbances, often occurring in ‘waste’ areas including logging roads and heavily grazed areas, disturbed woods and forest clearings and waterways.

Impact & Risks

Hound’s-tongue can form dense populations that displace native plant species and hinder the re-establishment of valuable range species, thereby decreasing availability of forage to wildlife and livestock. Plants are also toxic to livestock, although the fresh plant is considered unpalatable and generally avoided. The barbed seeds of hound’s tongue are a major source of spread and a general nuisance to recreationists, easily attaching to clothing and equipment. Seeds may also attach to wool and fur of cattle and horses, resulting in reduced sale value, stress on animals and extra time and money for removal.

Prevention & Mitigation

The most effective way to ensure that your lands do not become infested with hound’s-tongue is by prevention. Here are some recommendations to prevent invasion on your property:

  • Learn to identify hound’s-tongue and other invasive plants
  • Don’t let hound’s-tongue plants go to seed.
  • Maintain you land in a healthy, vigorous condition to ensure a productive plant community; competitive perennial grasses and forbs utilize water and nutrients that would otherwise be readily available to hound’s-tongue.
  • Follow a well-designed grazing management plan; excessive livestock grazing reduces competition and favours weeds.
  • Regularly patrol your property for hound’s-tongue plants and immediately treat new infestations.
  • Cooperate with adjacent landowners and encourage them to control hound’s-tongue
  • Re-vegetate disturbed, bare soils to a competitive perennial forage cover immediately after disturbance.
  • Clean burrs from animals and from clothing and shoes before leaving infested areas.
Treatment & Disposal

Hand pulling, hoeing and tillage can be effective for small populations of hound’s-tongue, but must be conducted before the plant sets seed. First-year hound’s-tongue plants are difficult to control by above-ground cutting, as nutrient reserves of the taproot allow defoliated plants to survive. Plants that are defoliated at the rosette stage may delay flowering for a year and thus result in a larger plant with a greater seed output. Mowing or clipping second year plants can reduce seed production, provided that it is done before seeds are formed. Response of hound’s-tongue after serious defoliation depends on the vigour of plants and the fertility of the site, especially nitrogen availability. Plants with low growth rates respond quite poorly to defoliation, while vigorous plants may recover and set seed. For very large infestations, it may be difficult to get enough labour for cutting or hand-pulling. Chemical control is also an option. Before applying herbicides, read the label for full use and precautionary instructions. Consult the most recent edition of the Alberta Agriculture and Forestry Crop Production Guide for the selection and application of chemicals to protect your crop. The root-mining weevil, Mogulones crucifer, has been released in BC and has proven to be very effective at reducing outbreaks of hound’s-tongue. Young beetles or larvae feed primarily on the root; however, if food is in short supply they will attack any part of the plant. Mature adult beetles reproduce through the summer months and heavily feed on plants.

Okanagan Distribution

Priority Level Definitions

Watch For - Poses a significant threat (very high risk) and does NOT presently occur in the region OR is relatively new to the region and is very limited in extent.
High - High risk/impact; limited population with significant potential to spread in the region.
Medium - Medium risk/impact; limited distribution – broader population distribution with potential to spread further in a region.
Low - Low risk/impact; may be widespread or not, may be of concern in specific situations with certain high values – e.g. specific agriculture crops. Some species may be treated primarily with biological control agents.