Hound’s tongue, gypsy flower or dog bur (Cynoglossum officinale) is a biennial, invasive weed introduced to North America from Europe. It is found in most states and is listed in many western states, including Colorado, as an important noxious weed.

A member of the borage family, hound’s tongue gets its name from the soft, tongue shaped leaves (Cynoglossum is Greek for “dog’s tongue”). It closely resembles the blue-flowered Chinese ‘Forget-me-not’ (Cynoglossum amabile). As a biennial, the first year’s growth consists of a rosette of many tongue-shaped, hairy leaves, ranging from 6-12 inches in length, arising from a thick, woody taproot. The second year the plant produces a flower stalk, 1-3 feet in height, with alternate leaves getting smaller towards the top of the stem.

Multiple flower stems arise from the upper leaf axils. The flowers are produced sequentially at the ends of the stems, and are reddish-purple, with five rounded petals (see picture). The fruits consist of four flattened, oval nutlets covered with hooks like Velcro. These hooks stick to animal hair and people’s clothing, thus aiding in seed dispersal. After flowering and setting seed, the plant dies and new plants germinate from seeds produced.

Hound’s tongue not desirable on property because it is very invasive and will out-compete grasses and other useful plants. Of particular importance to horses and livestock, it is poisonous and can cause untreatable liver disease. Animals will generally not eat the green plant unless they have nothing else to graze. However, since hound’s tongue frequently invades hay meadows, it can be readily incorporated in hay. When dried in hay, hound’s tongue remains poisonous, and is palatable and readily eaten by animals. A single mouthful of the plant is not poisonous, but if the dried leaves in the hay are consumed over the course of several months, the toxic alkaloids gradually destroy the animal’s liver. The toxic alkaloids are cumulative in effect, causing initial weight loss and signs of liver failure that eventually will cause death of the animal.

Another undesirable feature of hound’s tongue is the problem of the nutlets becoming entangled in pet hair, and wool of sheep and alpacas, devaluing the fleece.

Photo by Tony Knight
Hound’s tongue showing the rosette of leaves, and last year’s dried flower stalk. Inset picture is the flowers and fruits (nutlets).

The authors have received training through Colorado State University Cooperative Extension's Master Gardener program and is a Master Gardener volunteer for Larimer County.

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This page updated:  May 30, 2007