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Cynoglossum officinale

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Plant Profile

Flowering Months:
Boraginaceae (Borage)
Life Cycle:
Maximum Size:
1 metre tall
Fields, grassland, hedgerows, sand dunes, seaside, wasteland, wetland, woodland.

Variable in colour, 5 petals
Usually maroon flowers but also can be blue, purplish-pink or white. The flowers measure between 6 and 10mm across. The flowers look similar in appearance to Forget-me-not flowers. Pollinated by insects.
a flattened nutlet with a thickened flange. The fruit are covered in short hooked bristles which cling to clothing very easily. The seeds ripen in August and September.
An annual or biennial flower with simple, broad lanceolate, greyish-green leaves. Covered in soft hairs.
Smells unpleasant. The alternative name of Rats and Mice is sometimes given to Houndstongue because of it's disagreeable fragrance.
Other Names:
Beggar's Lice, Common Dog's Tongue, Common Hound's Tongue, Dog Bur, Dog's Tongue, Gypsy Flower, Hound's-tongue, Houndstooth, Rats and Mice, Rose Noble, Sheep Lice, Tory Weed, Wood Mat.
Frequency (UK):
Occasionally seen  

Other Information


Cynoglossum officinale, also known as houndstongue or gypsyflower, is a perennial herb native to Europe and Asia. It has naturalized in many parts of North America. The plant has hairy leaves and stems and produces small, bell-shaped blue or purple flowers. Houndstongue is considered a noxious weed in many areas, particularly in rangelands, as it is toxic to grazing animals and can cause mouth and tongue irritation. It is also toxic to humans if ingested in large quantities. Control methods include chemical, cultural, and biological methods.


Houndstongue, scientifically known as Cynoglossum officinale, is a biennial or perennial herb that belongs to the Boraginaceae family. This plant is native to Europe and Asia but has now been introduced and naturalized in North America, especially in the western region of the United States.

Houndstongue is a medium-sized plant that can grow up to 1 meter tall. It has rough and hairy stems, with dark green, oval-shaped leaves that are also hairy. The plant produces small, bell-shaped flowers that are reddish-purple in color and bloom in clusters from May to August.

The most distinctive feature of houndstongue is its seed pods. These pods are covered with small hooked bristles, which can easily attach to clothing, fur, or skin. This is where the plant gets its common name - houndstongue - because the seed pods resemble a dog's tongue.

While houndstongue may seem like a harmless plant, it is actually considered a noxious weed in many areas, including the western United States. This is because the plant is toxic to livestock and wildlife if ingested. The plant contains a toxin called pyrrolizidine alkaloids, which can cause liver damage, respiratory problems, and even death in animals that consume it.

In addition to its toxic properties, houndstongue can also crowd out native plant species and reduce biodiversity in ecosystems where it grows. The plant is highly invasive and can quickly spread through seeds, which can remain viable in the soil for several years.

Controlling houndstongue can be challenging, but there are several methods that can be effective. Hand-pulling or digging up the plants can be effective for small infestations, but for larger areas, herbicides or biological controls may be necessary. Biological control involves using insects or other organisms that feed on houndstongue to help control its growth and spread.

Houndstongue is not only a noxious weed but it also has a history of medicinal use. In traditional medicine, houndstongue was used to treat a variety of ailments such as coughs, inflammation, and wounds. However, it is important to note that the plant's toxicity makes it potentially dangerous for human consumption, and there is no scientific evidence to support its medicinal use.

In addition to its toxicity, houndstongue also poses a threat to agriculture. The plant can reduce crop yields and contaminate hay and forage, making it unsuitable for livestock feed. This can lead to economic losses for farmers and ranchers.

To prevent the spread of houndstongue, it is important to be aware of its presence and take steps to control its growth. This includes avoiding planting houndstongue in gardens or landscaping, properly disposing of any plant material or seeds, and monitoring areas where the plant has been identified.

In some states, including Montana and Wyoming, houndstongue is considered a noxious weed and is subject to control measures under state law. This may include mandatory reporting of sightings, as well as requirements for landowners to control the plant on their property.

Houndstongue is not the only plant in the Boraginaceae family that contains pyrrolizidine alkaloids. Other plants in this family, including comfrey (Symphytum spp.), Russian knapweed (Acroptilon repens), and tansy ragwort (Senecio jacobaea), also contain these toxic compounds. Like houndstongue, these plants are considered noxious weeds in many areas and can have negative impacts on ecosystems and livestock.

Toxicity from pyrrolizidine alkaloids can occur through direct ingestion of the plants or through the consumption of milk or meat from animals that have ingested the plants. In humans, exposure to these compounds can cause liver damage and other health problems.

Due to the potential risks associated with pyrrolizidine alkaloids, several countries have implemented regulations to limit their presence in food and herbal products. In the United States, the Food and Drug Administration (FDA) has established guidance on the safe levels of these compounds in food and dietary supplements.

In addition to the risks associated with pyrrolizidine alkaloids, the control of houndstongue and other invasive plants can also have unintended consequences. For example, the use of herbicides to control houndstongue may also harm non-target plants and wildlife. Careful management and control methods that take into account the potential impacts on the environment are necessary to minimize these unintended consequences.

The spread of houndstongue and other invasive plants is often facilitated by human activities such as transportation and development. Seeds can be transported long distances on vehicles, equipment, and clothing, and disturbed soil can create ideal conditions for the growth of these plants. This highlights the importance of education and outreach efforts to raise awareness about the risks associated with invasive plants and promote responsible land use practices.

In addition to management and control efforts, some organizations are also working on developing innovative solutions to address the challenges posed by invasive plants. For example, researchers are exploring the use of drones equipped with sensors to map and monitor invasive plant populations, which could help identify areas in need of management and control efforts.

Another area of focus is the development of new technologies and products that can help prevent the spread of invasive plants. For example, some companies are developing plant-based herbicides that are safer for the environment and non-target plants and wildlife. Other products, such as seed coatings and barriers, can help prevent the spread of invasive plant seeds.

Ultimately, addressing the challenges posed by invasive plants such as houndstongue requires a multi-faceted approach that combines education, outreach, management, and innovation. By working together, we can help protect our natural resources and ensure a healthy and sustainable environment for future generations.


Houndstongue filmed at Formby, Lancashire on the 8th May 2023.


Music credits
Radio Rock by Audionautix is licensed under a Creative Commons Attribution 4.0 license.

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